Tag Archives: FX

Sensor Size and Depth of Field

It is commonly said that crop sensor cameras make images having both a narrower field of view and a greater depth of field. Well, that's partly right. (Bill Ferris)

It is commonly said that crop sensor cameras make images having both a narrower field of view and a greater depth of field. Well, that’s partly right. (Bill Ferris)

It is well-known that a lens of a given focal length will deliver different angles of view when used with cameras having different sized sensors. For example, the above image was made with a Nikon D90 and a Nikkor 200-500mm f/5.6E telephoto zoom lens at 500mm. The D90 is a DX format camera having a 1.5x crop factor. In other words, the DX sensor crops the outer portion of the image formed by the lens. As a result, photographs made with this camera will display an angle of view equivalent to that produced by a lens with 1.5x the actual focal length used. In the above image, the 200-500 is at 500mm but the angle of view matches that produced by a 750mm lens.

It is often said that a crop sensor camera will also produce an image having a greater depth of field. In other words, the same lens at the same focal length will produce, not just a wider angle of view when paired with a full frame camera, but also a shallower depth of field. The claim is that the DX sensor not only crops the angle of view but forces a significant increase in depth of field. That assertion is just plain wrong.

In the below test images, you’ll see side-by-side comparisons of photos made with Nikon FX (full frame) and DX (crop sensor) camera bodies. The cameras used were the full frame Nikon D610 and the DX format Nikon D90. These cameras were used with the following lenses:

  • Nikkor 200-500mm f/5.6E VR
  • Tamrom 70-200mm f/2.8 Di VC USD
  • Tamron 24-70mm f/2.8 Di VC USD

To isolate sensor size as the only variable, the comparison images were made with the lenses at the same focal length, focal ratio and at the same distance from a fixed position subject. The Nikkor 200-500mm f/5.6E and Tamron 70-200mm f/2.8 Di VC USD were mounted on a tripod in a fixed position. The Tamron 24-70mm f/2.8 Di VC USD has no tripod collar or foot. The cameras were mounted to the tripod with the tripod in the same position for each set of exposures.

To create a large enough set of images to suitably address the question, each lens was used at a multiple focal lengths:

  • Nikkor 200-500mm f/5.6E VR: 200mm, 300mm, 400mm and 500mm
  • Tamrom 70-200 f/2.8 Di VC USD: 70mm, 100mm, 135mm and 200mm
  • Tamron 24-70 f/2.8 Di VC USD: 50mm and 70mm

Each lens was used wide open at its smallest f-stop number. ISO and shutter speed were kept constant for exposures made at the same focal length with both cameras.

Why did I decide to test the notion that sensor size has a significant impact on depth of field? I performed this experiment to test my belief that that lens aperture and distance to subject are the two factors having the greatest impact on depth of field. In other words, if a lens is used at the same physical aperture and distance to make photographs of a fixed position subject with two cameras of different sensor size, the depth of field recorded in the two images should be identical or, at least, very nearly so.

If I’m correct in this belief, the images should confirm it. If I’m wrong and if crop factor needs to be applied to depth of field as well as to focal length, photos made under the above conditions should exhibit obviously different depths of field with the photo made using the full frame camera consistently displaying an obviously shallower depth of field than the photo made using the crop sensor body.

Keeping all this in mind, let’s go to the photos. Below, are ten composite images. The photo occupying the left half of each composite was made using the Nikon D610. The photo to the right of the divider was made using the Nikon D90. Since the same lens at the same focal length, f-stop and distance to subject was used to make each image in a composite, the image made with the crop sensor D90 (on the right) shows a narrower angle of view. In each composite, I’ve indicated similar sections of the two photos that, when compared, reveal both photos to have identical – or nearly so – depths of field. This conclusion is reached by comparing the relative size of the subject, a hula dancer toy, and the out of focus highlights and details in the background.

Comparison #1: Nikkor 200-500mm f/5.6E (200mm, f/5.6)

The photo to the left of the divider was made with the Nikon D610 and Nikkor 200-500mm f/5.6E at 200mm, f/5.6, ISO 400, 1/200-second. The photo on the right was made with the same lens at the same distance from subject also at 200mm, f/5.6, ISO 400, 1/200-second. (Bill Ferris)

The photo to the left of the divider was made with the Nikon D610 and Nikkor 200-500mm f/5.6E at 200mm, f/5.6, ISO 400, 1/200-second. The photo on the right was made with the Nikon D90, the same lens at the same distance from subject also at 200mm, f/5.6, ISO 400, 1/200-second. (Bill Ferris)

Comparison #2: Nikkor 200-500mm f/5.6E (300mm, f/5.6)

The photo to the left of the divider was made with the Nikon D610 and Nikkor 200-500mm f/5.6E at 300mm, f/5.6, ISO 400, 1/200-second. The photo on the right was made with the same lens at the same distance from subject also at 300mm, f/5.6, ISO 400, 1/200-second. (Bill Ferris)

The photo to the left of the divider was made with the Nikon D610 and Nikkor 200-500mm f/5.6E at 300mm, f/5.6, ISO 400, 1/200-second. The photo on the right was made with the Nikon D90, the same lens at the same distance from subject also at 300mm, f/5.6, ISO 400, 1/200-second. (Bill Ferris)

Comparison #3: Nikkor 200-500mm f/5.6E (400mm, f/5.6)

The photo to the left of the divider was made with the Nikon D610 and Nikkor 200-500mm f/5.6E at 400mm, f/5.6, ISO 400, 1/250-second. The photo on the right was made with the same lens at the same distance from subject also at 400mm, f/5.6, ISO 400, 1/250-second. (Bill Ferris)

The photo to the left of the divider was made with the Nikon D610 and Nikkor 200-500mm f/5.6E at 400mm, f/5.6, ISO 400, 1/250-second. The photo on the right was made with the Nikon D90, the same lens at the same distance from subject also at 400mm, f/5.6, ISO 400, 1/250-second. (Bill Ferris)

Comparison #4: Nikkor 200-500mm f/5.6E (500mm, f/5.6)

The photo to the left of the divider was made with the Nikon D610 and Nikkor 200-500mm f/5.6E at 500mm, f/5.6, ISO 400, 1/250-second. The photo on the right was made with the same lens at the same distance from subject also at 500mm, f/5.6, ISO 400, 1/250-second. (Bill Ferris)

The photo to the left of the divider was made with the Nikon D610 and Nikkor 200-500mm f/5.6E at 500mm, f/5.6, ISO 400, 1/250-second. The photo on the right was made with the Nikon D90, the same lens at the same distance from subject also at 500mm, f/5.6, ISO 400, 1/250-second. (Bill Ferris)

Comparison #5: Tamron 70-200 f/2.8 VC (70mm, f/2.8)

The photo to the left of the divider was made with the Nikon D610 and Tamron 70-200mm f/2.8 VC at 70mm, f/2.8, ISO 400, 1/400-second. The photo on the right was made with the same lens at the same distance from subject also at 70mm, f/2.8, ISO 400, 1/400-second. (Bill Ferris)

The photo to the left of the divider was made with the Nikon D610 and Tamron 70-200mm f/2.8 VC at 70mm, f/2.8, ISO 400, 1/400-second. The photo on the right was made with the Nikon D90, the same lens at the same distance from subject also at 70mm, f/2.8, ISO 400, 1/400-second. (Bill Ferris)

Comparison #6: Tamron 70-200mm f/2.8 VC (100mm, f/2.8)

The photo to the left of the divider was made with the Nikon D610 and Tamron 70-200mm f/2.8 VC at 100mm, f/2.8, ISO 400, 1/400-second. The photo on the right was made with the same lens at the same distance from subject also at 100mm, f/2.8, ISO 400, 1/400-second. (Bill Ferris)

The photo to the left of the divider was made with the Nikon D610 and Tamron 70-200mm f/2.8 VC at 100mm, f/2.8, ISO 400, 1/400-second. The photo on the right was made with the Nikon D90, the same lens at the same distance from subject also at 100mm, f/2.8, ISO 400, 1/400-second. (Bill Ferris)

Comparison #7: Tamron 70-200mm f/2.8 VC (135mm, f/2.8)

The photo to the left of the divider was made with the Nikon D610 and Tamron 70-200mm f/2.8 VC at 135mm, f/2.8, ISO 400, 1/400-second. The photo on the right was made with the same lens at the same distance from subject also at 135mm, f/2.8, ISO 400, 1/400-second. (Bill Ferris)

The photo to the left of the divider was made with the Nikon D610 and Tamron 70-200mm f/2.8 VC at 135mm, f/2.8, ISO 400, 1/400-second. The photo on the right was made with the Nikon D90, the same lens at the same distance from subject also at 135mm, f/2.8, ISO 400, 1/400-second. (Bill Ferris)

Comparison #8: Tamron 70-200mm f/2.8 VC (200mm, f/2.8)

The photo to the left of the divider was made with the Nikon D610 and Tamron 70-200mm f/2.8 VC at 200mm, f/2.8, ISO 400, 1/400-second. The photo on the right was made with the same lens at the same distance from subject also at 200mm, f/2.8, ISO 400, 1/400-second. (Bill Ferris)

The photo to the left of the divider was made with the Nikon D610 and Tamron 70-200mm f/2.8 VC at 200mm, f/2.8, ISO 400, 1/400-second. The photo on the right was made with the Nikon D90, the same lens at the same distance from subject also at 200mm, f/2.8, ISO 400, 1/400-second. (Bill Ferris)

Comparison #9: Tamron 24-70mm f/2.8 VC (50mm, f/2.8)

The photo to the left of the divider was made with the Nikon D610 and Tamron 24-70mm f/2.8 VC at 50mm, f/2.8, ISO 400, 1/640-second. The photo on the right was made with the same lens at the same distance from subject also at 50mm, f/2.8, ISO 400, 1/640-second. (Bill Ferris)

The photo to the left of the divider was made with the Nikon D610 and Tamron 24-70mm f/2.8 VC at 50mm, f/2.8, ISO 400, 1/640-second. The photo on the right was made with the Nikon D90, the same lens at the same distance from subject also at 50mm, f/2.8, ISO 400, 1/640-second. (Bill Ferris)

Comparison #10: Tamron 24-70mm f/2.8 VC (70mm, f/2.8)

The photo to the left of the divider was made with the Nikon D610 and Tamron 24-70mm f/2.8 VC at 70mm, f/2.8, ISO 400, 1/640-second. The photo on the right was made with the same lens at the same distance from subject also at 70mm, f/2.8, ISO 400, 1/640-second. (Bill Ferris)

The photo to the left of the divider was made with the Nikon D610 and Tamron 24-70mm f/2.8 VC at 70mm, f/2.8, ISO 400, 1/640-second. The photo on the right was made with the Nikon D90, the same lens at the same distance from subject also at 70mm, f/2.8, ISO 400, 1/640-second. (Bill Ferris)

Comparing the above ten photo sets, it’s clear the photographs capture equivalent depths of field despite the fact that they’re made with full frame and crop sensor cameras. As expected, the crop sensor camera captures a more narrow angle of view. However, a comparison of the relative size of the hula dancer toy with the details of the out of focus background reveals that the DX format Nikon D90 captures the same depth of field as the FX format Nikon D610. This flies in the face of the common (but mistaken) belief that crop sensors significantly alter depth of field.

To understand the performance of each camera as illustrated in the above photos, one need only understand that photographic depth of field is largely determined by two factors: distance to subject and lens aperture. Each lens was kept at a constant position and distance from the subject for the photos made with the two camera bodies. By keeping focal length and f-stop constant in each photographic set, lens aperture was kept constant.

The f-stop number describes the ratio of lens focal length to aperture. In other words, a 200mm, f/5.6 lens has an aperture of about 36mm. This is true regardless of the size of the sensor in the camera to which the lens is attached. Here’s a listing of the focal lengths and apertures for each set of photos:

Nikkor 200-500mm f/5.6E VR

  • 36mm aperture (200mm, f/5.6)
  • 54mm aperture (300mm, f/5.6)
  • 71mm aperture (400mm, f/5.6)
  • 89mm aperture (500mm, f/5.6)

Tamron 70-200mm f/2.8 VC

  • 25mm aperture (  70mm, f/2.8)
  • 36mm aperture (100mm, f/2.8)
  • 48mm aperture (135mm, f/2.8)
  • 71mm aperture (200mm, f/2.8)

Tamron 24-70mm f/2.8 VC

  • 18mm aperture (50mm, f/2.8)
  • 25mm aperture (70mm, f/2.8)

As you review the above list, notice the constant f-stop results in increasing lens aperture as focal length increases. By keeping subject distance constant and increasing the physical aperture of the lens, depth of field becomes more shallow. By definition, the reverse is also true. With subject distance kept constant, decreasing lens aperture would result in a deeper or increased depth of field. And as illustrated by the above comparisons, keeping both subject distance and lens aperture constant produces constant depth of field. This holds true regardless of sensor size.

How is it, then, that so many photographers have come to accept the false assertion that crop sensor cameras make images having increased depth of field? The key to understanding this is the concept of equivalence. In simplest terms, equivalence describes two images made with different cameras and lens settings but having identical qualities. There are many factors that go into describing truly equivalent images. For the purposes of this discussion, we’ll focus on angle of the view and depth of field.

This set of images compares performance between crop sensor and full frame DSLR bodies. The images in the left column were made with a Nikon D90. Images in the right three columns were made with a Nikon D610. Both cameras used the same Tamron 70-200mm f/2.8 Di VC USD zoom lens, which was set up on a tripod to ensure it would not change position during the test. Both cameras used ISO 200, center point average metering and were operated in Aperture Priority. The subject in these photos is a scale model of the Lunar Excursion Module (LEM) from the Apollo program.

This set of images compares performance between crop sensor and full frame DSLR bodies. The images in the left column were made with a Nikon D90. Images in the right three columns were made with a Nikon D610. Both cameras used the same Tamron 70-200mm f/2.8 Di VC USD zoom lens, which was set up on a tripod to ensure it would not change position during the test. (Bill Ferris)

Let’s consider the above image set made with the Tamron 70-200mm f/2.8 VC. Due to its smaller sensor, a photograph made with the D90 captures a more narrow angle of view in comparison with an image made with the D610 at the same focal length. To capture an equivalent angle of view at the same distance from the subject, the D610 needs to use a greater focal length. At that increased focal length, the FX format camera will capture an angle of view equivalent to that recorded by the D90.

If both lenses are used at the same f-stop of f/2.8, their respective apertures will be about 46mm for the 130mm, f/2.8 lens on the D90 and 71mm for the 200mm, f/2.8 lens on the D610. Bear in mind, both cameras are at the same distance from the subject. Due to the larger physical aperture of the 200mm focal length lens, it records a shallower depth of field. To match the depth of field of the D90, the D610 is closed down from f/2.8 to f/4. This closes the aperture from 71mm to 50mm, which roughly matches the depth of field recorded by the D90 and its 46mm aperture.

Also, compare the quality of the out of focus background detail in the photos made with the DX format D90 (left most column) with the same detail in the second set of photos made with the FX format D610 (middle of three columns). Pay particular attention to the grouping of four bokeh balls to the left of the lunar lander model. In the D90 photos and in the equivalent D610 photos (right most column), that grouping is well defined with clear separation. In the middle column of D610 photos, that grouping is more diffuse, less well defined and not as clearly separated from the background.

This is what we would expect, considering that all the photos in that collection were made with the cameras and lenses at the same distance from the subject. The first and third column sets of images made with the D610 were made with the same lens aperture as the D90. The third column set of D610 images were made at an equivalent focal length to the D90 images. Both the angle of view and depth of field are equivalent. The first set (left column) of D610 images, while showing a wider angle of view, have equivalent depth of field as the D90 images. Again, this is exactly what one would expect given that the D90, and first and third set of D610 images were made at the same aperture, while the second set (middle column) of D610 photos were made at a larger aperture.

Another approach to producing equivalent depths of field, would have been to increase the lens aperture on the D90. The D90 would need a 130mm f/1.8 lens, which would have a 72mm aperture. That’s very nearly identical to the 71mm aperture of the 200mm, f/2.8 lens on the D610.

If equivalence is your objective, applying the crop factor to the f-stop allows you to calculate the aperture needed to make a photograph having an equivalent depth of field at a focal length delivering an equivalent angle of view. This adjustment can go either way. We can use a larger f-stop (multiply by the crop factor) to close down the aperture of the lens on the larger sensor camera or we can use a smaller f-stop (divide by the crop factor) to open the aperture of the lens on the smaller sensor camera. Either approach will produce equivalent apertures on the two cameras, which allows them to capture matching depths of field.

This is what has led so many photographers to mistakenly conclude that crop sensors significantly alter depth of field. What folks overlook is that the crop factor is applied to allow the lenses on the cameras to operate at the same physical aperture. Again, the key to understanding depth of field is recognizing that distance to subject and lens aperture are the critical factors. If you keep subject distance constant, keeping lens aperture constant will deliver equivalent depth of field. This holds true even if the lenses are used at focal length delivering non-equivalent angles of view.

Wildlife photographers often choose to shoot with crop sensor cameras to effectively bring the animals closer. They want the narrower angle of view delivered by the crop sensor. Shooting at 500mm f/4 with a DX camera will not only produce a larger image of the subject (in comparison with a photograph made using the same lens at the same distance on an FX camera), the DX camera will also record the same shallow depth of field and beautiful, buttery bokeh. That’s a huge advantage and a big reason why crop sensor cameras are so popular with sports and wildlife photographers. Of course, the smaller sensor also captures less total light with each exposure and this has implications for image noise. But that’s another blog entry.

In the meantime, armed with this new information and understanding of the role lens aperture plays in depth of field, let’s get out and shoot.

Bill Ferris | March 2016

What the f/#?

The Tamron 70-200 f/2.8 Di VC USD zoom lens has a focal ratio of f/2.8. This defines the largest aperture the lens is capable of having at all focal lengths throughout the zoom range. Operating at f/2.8, the focal length selected will be 2.8X the size of the aperture. While the focal length range is 70-200mm, the range of largest apertures is 25mm at a 70mm focal length to 71mm at 200mm focal length.

The Tamron 70-200 f/2.8 Di VC USD zoom lens has a constant focal ratio of f/2.8. This defines the largest aperture the lens will have throughout the zoom range. Operating at f/2.8, the focal length selected will be 2.8X the aperture. With a focal length range of 70-200mm, the widest aperture varies from 25mm at a focal length of 70mm to 71mm at a 200mm focal length. (Bill Ferris)

Let’s nerd out with some tech talk. Let’s chat about focal ratio.

Focal ratio is a rarely seen or heard phrase in online photography blogs and forums, which is surprising when you consider the important role focal ratio plays in photography. Focal ratio describes the size of a lens’s focal length relative to its aperture. It is typically expressed as an f-number, such as f/2.8. Ironically, when photographers start talking about lens aperture, it’s more than likely they’re actually discussing focal ratio. Let’s see if we can sort all this out.

We’ll begin at the beginning. Focal length is typically the first number mentioned when describing a lens. A 50mm lens has a focal length of, wait for it…50mm or roughly two inches. One may be inclined to think focal length is the distance from the front of the lens to the back, but it’s not. Focal length is the distance from the optical center of the lens to the image plane (film or sensor) where the image is formed. The optical center is usually inside the lens and is sometimes referred to as the point of convergence; the point where two light rays converge and cross.

The above diagram shows a cross section of the Nikkor 50mm f/1.4 lens. The focal length of the lens is 50mm, which is measured from the optical center of the lens to the image plane at the sensor.

The above diagram shows a cross section of the Nikkor 50mm f/1.4 lens. The focal length of the lens is 50mm, which is measured from the optical center of the lens to the image plane at the sensor.

Focal length determines how much the image is magnified. This is typically described as the angle of view produced by the lens. A 50mm lens produces a 47° (on a diagonal) angle of view at the image plane of a 35mm camera body. A 24mm lens delivers an 84° angle of view and a 200mm lens presents a 12° angle of view. Since the angle of view produced by a 50mm lens is similar to that of normal vision, it is known in 35mm photography as a normal lens. 24mm is a wide angle focal length and a 200mm is a telephoto lens.

Of course, 35mm is just one of many photographic formats. A photographic format is defined by the physical size of the medium used to record the image. In film photography, 35mm describes the length of the long side of a slide or film negative. Today’s digital cameras use light-sensitive CMOS sensors to record images. In full frame digital cameras, the sensor measures 36mm on the longest side. APS-C digital cameras have sensors that are about 23mm on the longest side. The camera in your smartphone or tablet is probably built around a sensor no larger than about 10 millimeters. What does sensor size have to do with this topic? A lot.

The above diagram illustrates the relative sizes of common digital camera sensor formats. The largest shown is a full frame (FX) sensor. The smallesst (lower left corner) is representaive of a typical smart phone (1/2.3") sensor.

The above diagram illustrates the relative sizes of common digital camera sensor formats. The largest shown is a full frame (35mm equivalent) sensor. The smallest (lower left corner) is representative of a smartphone (1/2.3″) sensor.

The smaller the sensor or film medium, the farther you need to be from your subject to match the field of view delivered by a given focal length lens. Imagine standing 10 feet from your subject with a full-frame DSLR camera and framing your subject head-to-toe using a normal 50mm lens. If you were to mount the same lens on an APS-C camera body, that camera’s smaller sensor would cut off or crop a portion of the image produced by the lens. You would need to step back to a distance of about 15 feet to reproduce the angle of view you had with the full frame camera body.

Another factor to consider when shooting with a “crop sensor” body is the effect of sensor size on depth of field. Depth of field (DOF) is the range of distances – nearest to farthest – in an image that appear acceptably sharp and in-focus. DOF is determined by magnification (lens focal length) and by the lens focal ratio or f-number. In a nutshell, bringing the subject closer decreases depth of field. Moving the subject farther away increases depth of field. As depth of field increases, a deeper portion of the image appears in focus. As depth of field decreases, only a narrow or shallow range looks sharp and in focus.

Both photographs were made using a Nikon D610 with Tamron 70-200 Di VC USD zoom lens at 125mm. The image on the left was shot at f/2.8 and has a much shallower depth of field. The image on the right was shot at f/32 and presents a much wider depth of field.

The above photographs were made using a Nikon D610 and Tamron 70-200mm f/2.8 Di VC USD zoom lens at 125mm. The image on the left was shot at f/2.8 and has a much shallower depth of field. The image on the right was shot at f/32 and shows much more of the field in focus.

As mentioned, focal ratio also has an effect on depth of field. For any given focal length, increasing focal ratio (making the f-number larger) increases depth of field while decreasing focal ratio (making the f-number smaller) reduces depth of field. We’ve already discussed the cropping effect of shooting with a smaller sensor. Stepping back to reproduce a desired angle of view increases depth of field. Zooming or changing lenses to shoot with a shorter focal length (to match the field of view provided by a full frame sensor body) increases depth of field.

One can compensate for the increased depth of field which results from the adjustments commonly made to expand the angle of view delivered by a crop sensor camera by shooting with smaller f-numbers. For example, shooting with a 35mm lens at f/1.4 will allow an APS-C sensor body to produce photographs having the same framing and depth of field as images made from the same position using a 50mm f/2.0 lens on a full frame body.

Let’s explore this in a bit more detail. Suppose you’re shooting with two cameras, one full frame and the other a crop sensor, and using the same 50mm lens with both. Its effective focal length (the focal length matching the angle of view delivered to the sensor) will be 50% longer or 75mm on the APS-C body. At f/4, the 50mm lens will have an aperture of 12.5mm. If we step back to compensate for the more narrow angle of view, the effective focal ratio (the focal ratio delivering an equivalent depth of field from the distance at which this lens matches the angle of view delivered to a full frame camera) will be f/6. Its effective 75mm focal length divided by the 12.5mm aperture equals six.

Do you see the relationship? We’re using an f/4 lens on an APS-C body. When the goal is to match the angle of view and depth of field produced by a full frame camera, we can determine the effective focal ratio at which a crop sensor camera needs to operate by dividing the focal ratio of the lens by the crop factor. The crop factor is 1.5 and the effective focal ratio (for depth of field) is f/6.

Here’s an illustration.

These images illustrate how to use a crop sensor camera to match both the angle of view and the depth of field delivered by a full frame body. I used a Nikon D610 and Nikon D90 to make photographs of the same toy caboose. Both cameras used a Tamron 70-200 f/2.8 Di VC USD lens. The lens was mounted on a tripod and the bodies switched out to ensure the lens would not move from its position during the test. The D610 uses a 36mm sensor and shot at 105mm, f/4 to make both images. The D90 uses an APS-C sensor with a 1.5X crop factor. I shot at 75mm, f/4 to make the first image. Comparing the first (top) images, we see that the D90 delivered a similar angle of view as the D610 but a comparison of the background shows the D610 to have a more shallow depth of field. The background in the D90 image is just skosh nearer to being in focus. For the second image, I applied the conversion factor and shot with the D90 at 70mm, f/2.8. A comparison of this image with the D610 image shows both to have delivered similar angles of view and similar depth of field. (Bill Ferris)

These images illustrate how to use a crop sensor camera to match both the angle of view and the depth of field delivered by a full frame body. I used a Nikon D610 and Nikon D90 to make photographs of the same toy caboose. Both cameras used the same Tamron 70-200 f/2.8 Di VC USD lens. The lens was mounted on a tripod and the bodies switched out to ensure the lens would not move from its position during the test. The D610 is built around a 36mm sensor and was used at 105mm, f/4 to make both images. The D90 has an APS-C sensor with a 1.5X crop factor. I shot at 70mm, f/4 to make the first image. Comparing the first (top) images, we see that the D90 delivered a similar angle of view as the D610 but a comparison of background detail reveals the D610 to have a more shallow depth of field. The background in the D90 image is just a skosh nearer to being in focus. For the second image, I applied the conversion factor and shot with the D90 at 70mm, f/2.8. A comparison of this image with the D610 image shows both to have delivered similar angles of view and similar depth of field. (Bill Ferris)

So, we’ve demonstrated that, in comparison with full frame cameras, crop sensor camera bodies produce images having narrower angles of view and, when adjustments are made to compensate for this, increased depth of field. We’ve also demonstrated that you can compensate for these performance factors. Either increase the distance between you and the subject or use a shorter focal length to increase the angle of view. Shoot at a smaller focal ratio (f-number) to make the depth of field more shallow. Next, we’ll explore the relationship between sensor size and length of exposure. Here’s a heads up, the outcome may not be what you expect.

I used my Nikon D610 (full frame) and Nikon D90 (APS-C) to take a series of exposures of a toy train engine. The toy steam engine was set up outside on a small tray table. The sky was overcast with nice, even lighting throughout the test. Both bodies used the same Tamron 70-200mm f/2.8 Di VC USD lens, which was set at 70mm. I selected ISO 200 on both cameras for all exposures. The zoom lens was set up on a tripod and the camera bodies were switched out without changing the position of the lens. I used each camera to make exposures at f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22 and f/32. I shot in aperture priority on both cameras and let their internal brains select the proper exposure.

Below, are pairs of images showing the photographs made at the same settings with the two bodies, side-by-side. All are unedited JPEGs. Keep in mind that the sensor in the D90 body cropped the image to match the angle of view produced by a 105mm lens.

In this comparison, photographs of the same subject made with a Nikon D610 (left) and a Nikon D90 (right) are shown, side-by-side. Both cameras shot at ISO 200. Both cameras used the same Tamron lens at 70mm. The lens was mounted on a tripod to ensure it would remain in the same position throughout the test. For each focal ratio, both cameras used the same exposure. (Bill Ferris)

In this comparison, photographs of the same subject made with Nikon D610 (left) and Nikon D90 (right) cameras are shown, side-by-side. Both cameras were set to ISO 200. Both cameras used the same Tamron lens at 70mm. The lens was mounted on a tripod to ensure it would remain in the same position throughout the test. At each focal ratio, both cameras metered the scene as having the same brightness and chose the same exposure. (Bill Ferris)

Let’s talk more about this f-number thing. You’ll recall that focal ratio describes the ratio of the focal length of the lens to the aperture of the lens. A 50mm lens at f/2.0 has a focal length that is 2-times its aperture. Therefore, the lens aperture at f/2.0 will be 25mm. At f/4.0, the aperture is 12.5mm; at f/8.0, 6.25mm and so on. The relationship between aperture and focal ratio is pretty straight forward: for any given focal length, decreasing aperture increases focal ratio and increasing aperture decreases focal ratio.

Rarely, however, do photographers talk about the f-number as a focal ratio. More commonly, they talk about it as a lens aperture. They talk about an f/2.0 lens having a larger aperture than an f/4.0 lens. It’s an accurate statement, if we’re talking about the same lens at different focal ratios. But this is just one of many scenarios where focal ratios are compared.

Let’s consider the scenario of discussing different lenses. Suppose we’re comparing a 50mm lens to a 100mm lens. Suppose the 50mm lens is being used at f/2 and the 100mm lens is set to f/4. One might think the 50mm lens, by virtue of having a smaller f-number, will have a larger aperture. In fact, both lenses have identical 25mm apertures. It simply isn’t the case that every f/1.4 lens has a larger aperture than every f/8 lens. In reality, it is quite common for a lens operating at a large f-number to have a larger aperture than a lens working at a small f-number. I would wager to guess that there isn’t a focal ratio at which a 600mm lens doesn’t have a larger aperture than the fastest focal ratio smartphone.

One quality that does translate across different lenses and cameras, is the speed of the imaging system. What does speed have to do with photography? To understand, it helps to think of a properly exposed photograph as one where a certain intensity of light needs to fall upon the sensor at the image plane. Think of light as water, the sensor as a container used to collect water (light) and the lens as the opening through which water is poured into the container.

That said – and this next point is critical – a properly exposed image is not determined by the total quantity of light delivered to the sensor. The length of a proper exposure is determined by the average brightness of the image falling on the sensor. To better understand this, we’re going to introduce a new concept: surface brightness.

The above illustrates the concept of Surface Brightness in photography. For a properly exposed image, the camera's optical system must collect and deliver light having a surface brightness (brightness or intensity per square millimeter) to the sensor. This is represented by the evenly deep layer of "blue" light collected bu the sensor. If you use the same lens on a crop sensor body, the same intensity of light (represented by the central red region) is delivered to the sensor. Being smaller, the crop sensor collects less total light. However, the surface brightness of the image (the brightness per square millimeter) is identical to that of the larger sensor. (Bill Ferris)

The above illustrates the concept of Surface Brightness in photography. For a properly exposed image, the camera’s optical system must collect and deliver light having a surface brightness (brightness per square millimeter) to the sensor. This is represented by the thick layer of “blue” light collected by the sensor. The thickness of the layer represents the intensity or average brightness of the image. If we use the same lens on a crop sensor body, the same intensity (thickness) of light is delivered to the sensor. This is represented by the central red zone on the sensor. Being smaller, the crop sensor collects less total light. However, the surface brightness of the image is identical to that of the larger sensor. (Bill Ferris)

Earlier, a correct exposure was described as one where a container (sensor) is filled to the correct depth (intensity) with water (light). It doesn’t matter if the container is large enough to hold one gallon or 100 gallons. As long as it’s filled to the proper depth, the exposure will be good. In this example, the depth of the water represents the average brightness of the image at the image plane. Another way to describe the average brightness or intensity of light, is to talk about image surface brightness.

Surface brightness is defined as a brightness per unit area. In photography, we can define surface brightness as the brightness of light per square millimeter falling on the film or sensor. It is not a total volume or quantity of light. Rather, it is an average intensity of light. Surface brightness is strictly determined by the focal ratio of the optical system. The lens f-number determines the length of the exposure needed to deliver light of a certain intensity to the sensor. A full frame camera, crop sensor camera and smartphone camera focused on the same subject – and all operating at f/2.0 – will deliver the same light intensity per square millimeter (the same surface brightness) to their respective sensors during the same length exposure.

The relative sizes of full frame (pink) and APS-C (blue) sensors is illustrated above. The effects of a crop frame sensor include an increase in effective focal length and an increase in effective depth of field.

The relative sizes of full frame (pink) and APS-C (blue) sensors is illustrated above. The effects of a crop frame sensor include an increase in effective focal length and effective depth of field.

Despite the fact that a crop sensor doesn’t collect as much total light during an exposure as a full frame sensor, the intensity or surface brightness of the images formed on both sensors will be the same. We saw this at work in the above illustrations comparing exposures made with the D610 and D90. Despite the fact that, during each set of exposures, the D90’s smaller sensor collected less total light than the full frame sensor of the D610, the image made by the D90 was still properly exposed. This is because the exposures made by both cameras produced images having identical surface brightness at the image plane.

This set of images compares performance between crop sensor and full frame DSLR bodies. The images in the left column were made with a Nikon D90. Images in the right three columns were made with a Nikon D610. Both cameras used the same Tamron 70-200mm f/2.8 Di VC USD zoom lens, which was set up on a tripod to ensure it would not change position during the test. Both cameras used ISO 200, center point average metering and were operated in Aperture Priority. The subject in these photos is a scale model of the Lunar Excursion Module (LEM) from the Apollo program.

This set of images compares performance between crop sensor and full frame DSLR bodies. The images in the left column were made with a Nikon D90. Images in the right three columns were made with a Nikon D610. Both cameras used the same Tamron 70-200mm f/2.8 Di VC USD zoom lens, which was set up on a tripod to ensure it would not change position during the test. Both cameras used ISO 200, center point average metering and were operated in Aperture Priority. The subject in these photos is a scale model of the Lunar Excursion Module (LEM) from the Apollo program.

The above illustration allows us to compare the performance of crop sensor and full frame cameras. The first column of D610 exposures matches the settings of the D90 images in the left-most column. Focal length and focal ratio are the same. In most cases, both cameras’ metering systems selected the same exposure. The most obvious difference between the D90 and first set of D610 images is the wider angle of view delivered by the full frame sensor. For the second set of D610 images, I zoomed in to match the effective focal length of the D90. The angles of view of these images closely match the corresponding D90 exposures. The second set of D610 images were shot at f/2.8 and clearly display a more shallow depth of field. For the third set of D610 photographs, I changed the focal ratio to match the depth of field presented in the D90 images. Notice that the exposures for these images are all 1/800-second. They’re longer to compensate for the larger focal ratio.

Focal Ratio is the key to understanding how different cameras, lenses and sensors are able to make good photographs using the same or similar length exposures. Focal ratio determines the length of time needed to collect enough light to make an image having the required surface brightness. For any two cameras operating at the same ISO and delivering the same angle of view, the exposure times will typically be the same.

So, the next time you read or hear a photographer talking about an f/1.4 lens having a larger aperture than an f/2.0 lens, stop and give that statement some thought. If the lenses being compared are a 20mm f/1.4 and a 50mm f/2.0, the 50mm lens will be operating with a larger aperture. The 50mm lens will have a 25mm aperture at f/2.0 and the 20mm, f/1.4 lens aperture will be just over 14mm. However, due to its faster focal ratio, the 20mm lens will deliver more light per square millimeter to the sensor, faster. Because the f/1.4 lens produces a brighter image – an image having a higher surface brightness – the length of the exposure will be shorter.

In photography, the objective is not to deliver the largest volume of light to the sensor. The objective is to deliver the needed intensity (surface brightness) of light to the sensor. Speed is everything and focal ratio is the key.

Now, get out there and shoot!

Bill Ferris | August 2015

Camera Settings – Wildlife Photography

An American White Ibis preens in the late afternoon light at Disney World Epcot theme park. (Bill Ferris)

An American White Ibis preens in the late afternoon light at Disney World Epcot theme park. (Bill Ferris)

This post continues a series on camera settings for specific genres of photography. As I mentioned in the first installment, I am not suggesting these settings will be best for every photographer. I am sharing them because they work for me and may be of some help to you.

As the above image indicates, this post will focus on settings for bird and wildlife photography. Let’s begin with my goals when shooting animals in a natural setting:

  • Communicate the wild
  • Convey the personality of the animal
  • Bring the viewer close

There is something about an animal in a wilderness setting that captures the imagination. This is particularly true in cultures that feel a strong connection to a past when people lived, struggled, thrived and died in wilderness places. They competed not only with the land and weather but also with animals. Some animals were hunted as sources of food and clothing. Others were hunted as competitors for scarce food resources or as threats to people.

A photograph of an animal in a wilderness setting has the potential to reconnect us with that pioneer heritage. It can make the pulse quicken and loose a surge of adrenalin in the blood. Communicating the wild is as much about setting as the animal, itself. Framing the shot with a rugged terrain or severe weather conveys a sense of wilderness. The personality of the animal comes to life through action. Interesting – even aggressive – behavior does the trick. Sometimes, the suggestion of a behavior that is about to happen can be even more compelling. Capturing the instant before the animal becomes aggressive hints at wildness and allows the audience’s imagination to fill in the rest.

The Kilimanjaro Safaris tour at Disney World Animal Kingdom exposes visitors to a host of animals native to Africa, including the giraffe. (Bill Ferris)

The Kilimanjaro Safaris tour at Disney World Animal Kingdom exposes visitors to a host of animals native to Africa, including the giraffe. (Bill Ferris)

A long telephoto lens can bring the viewer close enough to feel the breath of the animal. Stealth and patience, when skillfully employed, can have the same effect. Every guideline has its exceptions and this one is no different. A wide angle lens capturing the interesting behavior of a collection of animals in the wild can be just as inspiring.

Bird and wildlife photography is a relatively new interest for me. I’m still searching for that heart-stopping image of an apex predator in the wild, or an iconic creature persevering against nature’s maelstrom. However, the technique of capturing such moments is fairly well ingrained. I’ll be ready when the moment arrives. Here, are my settings:

  • Aperture: f/2.8 to f/5.6
  • ISO: ISO-auto with 1/500 to 1/1000-second as minimum shutter speed and 6400 as maximum ISO
  • Back Button Focus: AE-L/AF-L button assigned to autofocus control
  • Burst Rate: Low (3 fps) to Continuous High (6 fps)
  • Image Quality: RAW
  • Exposure Compensation:  +2/3 to 0 to -2/3 stop

I use a large aperture to blur the background and isolate the subject. A wide open aperture also allows for the use of more reasonable ISO’s when shooting early in the day. Now, an aperture closed one stop from wide open will do a better job of capturing pin sharp detail in the animal. So, if the light level will allow it and if there is significant distance between your subject and the background, consider closing down the lens a bit.

Back button focus is a great technique for just about any type of photography. It gives you more control over focus point and framing. If the animal is moving slowly, a shutter speed of 1/500-second will do an excellent job of freezing action. However, birds in flight and other more aggressive actions demand a faster shutter speed. A low burst rate works fine for an animal slowly grazing for food. A faster burst rate is called for when shooting birds in flight and other more dynamic action.

A bull Elk eyes a gathering crowd of tourists on the South Rim of Grand Canyon National Park. (Bill Ferris)

A bull elk eyes a gathering crowd of tourists on the South Rim of Grand Canyon National Park. (Bill Ferris)

Finally, you’ll want to pay attention to the coloration of an animal. Animals with dark fur may require an exposure compensation of +2/3 stop to preserve detail. By contrast, compensation of -2/3 stop will preserve feather detail when photographing a bright white bird.

These are the settings I use when photographing birds and animals. If you give them a try, I think you’ll find the results rewarding. At the very least, you’ll gain a better understanding of the settings that work best for you.

Now, get out there and shoot!

Bill Ferris | April 2015

Camera Settings – Sports Photography

NAU's Eddie Horn grabs a handful of facemask to prevent Eastern Washington's Quincy Forte from reaching the end zone

NAU’s Eddie Horn grabs a handful of facemask to prevent Eastern Washington’s Quincy Forte from reaching the end zone (Bill Ferris)

With this post, I’m launching a series in which I will share the settings I use for specific genres of photography. Each article will focus on one kind of photographry: landscape, wildlife, event, portraiture and, in this entry, sports.

Right off the top, I want to be clear about something. The settings I use are not necessarily best for everyone. In fact, I suspect the opposite may be closer to the truth. Many professional and experienced amateur photographers prefer to shoot in full manual mode. I don’t.

In any given situation, there are some settings I absolutely want to control and others I’m perfectly comfortable allowing the camera to control. It’s been my experience that modern digital cameras are reliably competent at choosing settings like shutter speed and ISO. Even if the setting the camera chooses is off by 1/3 to 1/2 a stop, shooting in RAW allows me to correct for that in post with just a few clicks of the mouse.

In short, the settings I use work for me and my workflow. My intent in sharing them in this series is that they may help you to make better photos and get more satisfaction from photography.

So, let’s get to it. Here, are the  settings I typically use with my Nikon D610 when shooting sports:

  • Mode: Aperture Priority
  • Aperture: f/2.8
  • ISO: ISO-auto with 1/1000-second as minimum shutter speed and 6400 as maximum ISO
  • Autofocus: Continuous with a 9-point cluster at the center
  • Back Button Focus: AE-L/AF-L button assigned to autofocus control
  • Burst Rate: Continuous High (6 fps)
  • Image Quality: RAW

Why? Let’s start at the beginning. Before I start shooting, I give some thought to what I want to accomplish with the photograph. Here are my goals for sports photography:

  • Capture the decisive moment
  • Communicate the emotion of that moment
  • Put the audience in the middle of the action

The above settings allow me to accomplish all three.

A goalkeeper prepares to send the ball out of her zone.

A goalkeeper prepares to send the ball out of her zone. (Bill Ferris)

The first decision I make when setting up the camera is selecting a mode to use. I never shoot in full Auto. In that mode, the camera makes all the decisions and I’ve yet to find a camera having an aesthetic identical to mine. I rarely shoot in Manual. In that mode, I make all the decisions and, frankly, that’s just a lot of work.

Aperture Priority allows me to lock in a focal ratio. Normally, I’ll set the lens to f/2.8. Since I’ll be using a fast shutter speed to freeze action, I need to deliver big heaping gobs of light to the sensor to produce a properly exposed image. Shooting at f/2.8 maximizes the light collected by the lens and delivered to the sensor, at any given moment.

A large aperture also produces an image with a shallow depth of field. That is a huge plus when shooting sports. Often, the shot is focused on one player, coach or person. But how to draw attention to someone who is surrounded by a melee of athletes, officials and fans? A shallow depth of field serves to isolate the subject by putting everything and everyone else out of focus.

With a wide aperture selected and locked in, the next choice is which shutter speed to use. For basketball, soccer and football, I have found a shutter speed of 1/1000-second does a great job of freezing the action. Now, I could do this by putting the camera in manual mode, selecting the aperture (f/2.8), shutter speed (1/1000-second) and ISO. But I’m lazy. I don’t want to be responsible for all three variables. I want the camera to do some of the work. I’ll choose the aperture and shutter speed, and let the camera choose the ISO.

This is why I use Nikon’s Auto-ISO setting. In this setting, you choose a minimum shutter speed and a maximum ISO. For sports, I select 1/1000-second and a maximum ISO of 6400. Shooting with the D610, I’ve been very pleased with the quality of images taken at ISO 6400

At this point, I’m almost ready to start shooting.

This photograph was taken with a Tamron 70-200mm at 135mm, f/2.8, ISO 3600, 1/640-second

This photograph was taken with a Tamron 70-200mm at 135mm, f/2.8, ISO 3600, 1/640-second (Bill Ferris)

Next, i check the image quality setting to confirm it’s still in RAW. Shooting in RAW serves several purposes. First, it is the format that captures and preserves the most information about each image. The more information there is at my disposal, the greater the flexibility I have in post. RAW allows for adjustments to be easily made in Lightroom, not just in exposure, but also in white balance, contrast and a host of other key settings. As such, shooting in RAW gives me the greatest latitude when processing an exposure. And since I’m trusting my camera to choose the ISO, RAW acts as my insurance policy against a setting that is off by as much as a full stop. Typically, however, the Nikon D610 is within 1/3-stop in the ISO it chooses.

To ensure that my photographs are properly focused, I use Nikon’s AF-C or continuous autofocus mode. In this mode, the camera continuously adjusts focus to keep the subject sharp, For most events, I’ll use a cluster of nine autofocus points – sometimes, a single point – to allow the camera to focus on the subject while ignoring distracting objects within the frame. The autofocus points at the center of the frame are most accurate. Hence my preference for a central grouping.

Now, to give myself more control over when and where focus is set, I also engage back button focus. This is a technique where you assign focus control to a button on the back of the camera body. I assign focus control to the AE-L/AF-L button on my Nikon D610. With back button focus engaged, I am able to push the AE-L/AF-L button when I want to set focus. If I’m shooting a stationary subject, I can set focus then remove my finger from the button and recompose. If the subject is moving, I’ll continue pressing the button and allow the camera to follow focus while I’m keeping the subject framed.

With 12-seconds left in regulation, NAU's Dan Galindo hauls in a Jordan Perry pass to score the game-winning touchdown

With 12-seconds left in regulation, NAU’s Dan Galindo hauls in a Jordan Perry pass to score the game-winning touchdown. (Bill Ferris)

Almost by definition, athletes are quick and fast-moving subjects. As such, I use my camera’s highest burst rate to rip 6-10 exposures in a 1-2 second burst. This gives me the best chance of capturing the decisive moment. The only thing that’s missing from the above photo, is the official’s arms in the air signaling a touchdown. But that didn’t happen until long after the receiver made the catch.

While we’re on the subject of moments, let’s address a setting that, all too often, is ignored. Moments are fleeting. As soon as you recognize one as being of significance, it is already gone. One of the keys to successful sports photography is anticipating a decisive moment, recognizing that it is about to happen. This has more to do with you, as a student of the game, than with your camera settings. Know the sport. Decide ahead of time the kind of moment you want (a score, a collision, the joy of victory, dignity in defeat), watch for that moment, recognize when it is about to happen and press the shutter release.

Now, get out there and shoot.

Bill Ferris | January 2015

Anticipation

NAU quarterback Chase Cartwright releases a pass toward receiver Ify Umodu

NAU quarterback Chase Cartwright releases a pass toward receiver Ify Umodu. Photograph made with Nikon D610, Tamron 70-200mm f/2.8 VC at 200mm f/2.8, ISO 4500, 1/1000-second. (Bill Ferris)

Sports photography is one of those disciplines where there is just no getting around the fact that the gear you need to consistently make great photos is expensive. Scan the sidelines at an NFL game and you’ll find twenty or more photographers. Each brings at least two camera bodies and numerous lenses to the game. Many will be shooting either the Canon 1DX or a Nikon D4s. The two most common lenses are long, fast telephotos: 300mm f/2.8 and 400mm f/2.8. If some conniving super thief were to devise a scheme to steal all that gear, they’d easily walk away with over $1 million in kit.

Why is sports photography so expensive? It all boils down to one thing: speed. The sports photographer needs a fast camera and fast lenses. The top Canon and Nikon professional camera bodies have burst rates in excess of 10 frames per second. In a profession where the job is to capture the defining moment and where the players have world-class size, strength and speed, the difference a tenth of a second can make is astounding. In that brief instant, a player can go from diving for the goal line to fumbling the football. The sports photographer needs a camera capable of capturing that moment.

Because of the speed at which the game is played, a sports photographer needs to use very short exposures to freeze the action. Yes, there are situations where a slow shutter speed can allow you to make an image that perfectly captures the astounding pace of the action. But in most circumstances, the objective is to freeze action. Exposures of 1/1000-second or faster are commonplace. To shoot at 1/1000-second, you need lenses that collect available light in big, slurping gulps.

A 400mm f/2.8 lens drinks light with gusto. It focuses in a blink and follows focus even as the player with the ball is doing everything possible to elude both you and the other team. It also delivers images having a very shallow depth of field. The subject is sharply focused but the background has a pleasing, soft creaminess. This creates separation between the subject and background, making for a better photo.

To shoot at 1/1000-second in an indoor stadium or at night, you need a camera body that makes great images with a minimum of light. To accomplish this demanding task, your camera sensor needs to make clean images at ISO’s of 4000 or higher. While the lighting at professional venues is typically pretty good, the light level at a collegiate venue is often much lower. The light levels at high school football stadiums makes you wonder how the players can find the end zone without using a flashlight. There is no escape from this. If you use longer exposures to allow the sensor time to collect more light at a lower ISO, the athletes will be blurred and the detail lost. Even indoors or at night, the sports photographer needs speed.

This level of performance is unavoidable and it’s not cheap. Are you familiar with the old phrase, “Cheap, fast and good; pick any two.” In sports photography, there is no such thing as cheap…not if you want to make great images.

Having the right equipment is only the start. The most critical tool available to the sports photographer is something that cannot be bought. That critical tool is knowledge and there is no substitute. If you know the game, you have the ability to anticipate where the next play is going. If you can anticipate where the next play is going, you have the opportunity to position yourself, to focus on the right athlete or place on the field and to be there ahead of all the other photographers to capture the decisive moment in the contest.

NAU running back Casey Jahn looks to turn a run north-south

NAU running back Casey Jahn looks to turn a run north-south. Photograph made with Nikon D610, Tamron 70-200mm f/2.8 VC at 200mm, f/2.8, ISO 3600, 1/1000-second. (Bill Ferris)

I recently had the opportunity to photograph my first NCAA football game. I’ve been a sports fan – particularly football – most of my life and have been working professionally in televised sports coverage for 25 years. In other words, I know the sport and I know what makes for a great sports image.

My photographic equipment can be accurately described as pro-sumer. I shoot with a Nikon D610 digital SLR camera body. Nikon classifies this as an Enthusiast level camera. The 24 megapixel full-frame sensor is among the best available in any digital camera. I’ve shot with it at ISO 6400 and been very pleased with the quality of the images. The 39-point auto focus system is good – not great, just good – and the burst rate is a respectable 6 frames per second. The buffer allows me to shoot at continuous high burst for 2-3 seconds before the camera will start choking on new image files.

Like most of you, I’m on a budget. So, when I made the move to full-frame, I went with third party lenses to maximize both performance and value. The Tamron line of f/2.8 Di VC USD lenses deliver both. I am primarily a landscape photographer who does occasional portraiture. The Tamron glass gives me a range of focal lengths and apertures that meet the needs of both disciplines. Best of all, they deliver excellent image quality at a fraction of the cost of the equivalent Nikon lenses.

I used the Tamron 70-200 f/2.8 Di VC USD zoom with my Nikon D610 body to shoot the football game. The D610 was set to aperture priority and I shot at f/2.8 throughout the game. I also used the D610’s auto-ISO feature to configure the camera to use a 1/1000-second  shutter speed and choose the ISO that would allow for the proper exposure. Auto focus was set to AF-C (continuous servo), with 9 central auto focus points selected. I did experiment a bit with offsetting the auto focus points to the left or right (top or bottom when shooting in portrait aspect) but invariably came back to the central auto focus point. I also experimented with the D610’s continuous focus lock setting, ultimately choosing a setting that is slightly more responsive to motion than the default configuration.

The first decision I had to make was where to position myself for the opening kickoff and first offensive series of the game. Now, I am an NAU employee and support my Lumberjack sports teams. That said, Eastern Washington entered the game as the 2nd-ranked team in FCS football. They were 7-1 on the season with their only loss being a 52-59 decision against the Washington Huskies. To be perfectly candid, I expected the Eagles to put up a lot of points against NAU so, I set up at the end of the field where they would be scoring. This decision paid off as Eastern Washington’s first touchdown of the game was scored at that end. Unfortunately, while reviewing the shots I’d made of the play, I realized a corridor labelled, RESTROOMS, was the prominent background element in the images. Note to self: always be aware of your background.

As the 1st quarter progressed, it was clear that NAU had come to play. They weren’t intimidated by Eastern Washington and were gradually building momentum. So when the end of the quarter arrived, I decided to stay at the south end of the field to be in position to capture a Lumberjack touchdown. That proved to be the right decision as, early in the 2nd quarter, NAU quarterback Chase Cartwright hit receiver Beau Gardner in the end zone for the Jacks’ first touchdown of the day. For that score, I was positioned to photograph the celebration with NAU cheerleaders and fans in the background.

Eastern Washington's Cooper Kupp skies over NAU defender Marcus Alford to score a touchdown

Eastern Washington’s Cooper Kupp skies over NAU defender Marcus Alford to score a touchdown. Photograph made with Nikon D610, Tamron 70-200mm f/2.8 VC at 90mm, f/2.8, ISO 4500, 1/1000-second. (Bill Ferris)

The Eagles blocked the extra point attempt and the two teams battled to a standstill for the next 8:00 as Eastern Washington held a narrow, 7-6, lead. Sensing that the Eagles were slowly reclaiming the momentum, I hustled to the north end zone to position myself for a possible Eastern Washington score. My instincts paid off as Cooper Kupp found the land of milk and honey on a 14-yard pass from Jordan West. I was positioned at the back corner of the end zone and had a great view of Kupp leaping over the pylon for the score. NAU battled back, scoring two field goals in the final 5:00 of the 2nd quarter to cut the EWU lead to, 14-12. Recognizing the shift in momentum, I moved to the south end of the field and made some nice photographs of Northern Arizona’s final drive of the half.

During halftime, I weighed the question of which team would come out of the locker room having made the correct adjustments. I gambled on NAU and set up at the north end zone. Almost immediately, I was questioning the decision as Eastern Washington marched right down the field. But the Jacks held them to a field goal and, on their next possession, Northern Arizona quarterback Chase Cartwright led the team on a drive that culminated on a 1st & goal from the 3-yard line. Seeing receiver Ify Umodu breaking out to my side of the field, I rolled the dice again, isolating on Umodu on the next play.

As a result, I completely missed a touchdown pass to NAU’s Alex Holmes. In hindsight, I should have continued employing the technique that had been working throughout the day of focusing on the quarterback, reading his body language after the snap and breaking for the receiver on the throw. I also decided I had been over thinking the game since the start of the half. So, I returned to a mode of trusting my gut instinct on where to go for the next series and then being smart about following the development of the play.

NAU's Eddie Horn grabs a handful of facemask to prevent Eastern Washington's Quincy Forte from reaching the end zone

NAU’s Eddie Horn grabs a handful of facemask to prevent Eastern Washington’s Quincy Forte from reaching the end zone. Photograph made with Nikon D610, Tamron 70-200mm f/2.8 VC at 112mm, f/2.8, ISO 5600, 1/1000-second. (Bill Ferris)

This strategy paid off on EWU’s next possession. I had gone back to the other end of the field, setting up on the Eastern Washington side. Running back Quincy Forte powered his way to the 1-yard line before being tackled by the face mask. I had a perfect angle on and view of the face mask tackle. On the very next play, Forte forced his way into the end zone right in front of me.

Eastern Washington had a 24-19 lead and the teams battled back-and-forth, trading field goals over the next 15-minutes. It was during the 2nd half that I identified the spot where I wanted to be when the game ended. The location offered two great options for backgrounds. One, was the NAU bench on the opposite side of the field. The other option was the NAU cheerleading squad along the back of the south end zone. Either would make a perfect background, if the Jacks were able to score a late touchdown to win the game.

When the Eagles took possession of the ball with 4:37 on the clock, I sensed a game-clinching score coming and worked my way through the EWU bench to the north end of the field. Facing a 4th & 4 at the Northern Arizona 23 yard line, Eastern Washington burned two timeouts in succession before going for it.  A conversion would have allowed the Eagles to run out the clock but Jordan West’s pass to Cooper Kupp fell incomplete.

The final seconds were setting up exactly as I’d hoped: Northern Arizona had the ball on their own 23 with no timeouts and :47 left on the clock. They needed a touchdown and would have to be aggressive in their play-calling. So, I hustled back to my spot at the south end zone and waited for the magic to happen.

With 12-seconds left in regulation, NAU's Dan Galindo hauls in a Jordan Perry pass to score the game-winning touchdown

With 12-seconds left in regulation, NAU’s Dan Galindo hauls in a Jordan Perry pass to score the game-winning touchdown. Photograph made with Nikon D610, Tamron 70-200mm f/2.8 VC at 70mm, f/2.8, ISO 8063 (Hi 0.3), 1/1000-second. (Bill Ferris)

On NAU’s second play, backup quarterback Jordan Perry completed a toss to Alex Holmes who sprinted 54 yards before going out of bounds at the Eastern Washington 20 yard line. On the next play, Perry took the snap and immediately looked to his left and my side of the end zone. As he cocked his arm and released the ball, I instinctively panned to pick up true freshman Dan Galindo breaking open across the goal line. Galindo was right in front of me as he cradled the ball, rolled across the turf and sprang up in celebration. With :12 left in the game, Galindo had just scored the go-ahead touchdown.

A huge celebration ensued as Galindo was surrounded by teammates. Team mascot, Louie the Lumberjack, even joined in. Cheerleaders and fans were frantic with joy. The Skydome was filled with the roar of fans who knew they were witness to something very special. Northern Arizona was about to defeat the number two team in the country. But there was more work to be done. NAU went for a 2-point conversion and failed. They squib kicked on the kickoff and Eastern Washington’s offense took the field with just :07 remaining. Their final desperation play ended when NAU defensive back Darius Lewis intercepted a backwards lateral and ran with the ball until time expired.

I immediately ran onto the field to capture the bedlam and ecstasy of the win. After making a few exposures with the 70-200, I ran over to my camera bag to exchange the telephoto zoom for the Nikon 16-35mm f/4 VR. I used this wide angle zoom to document the post-game celebration.

Jerome Souers, acknowledges the crowd after the comeback win versus Eastern Washington

Jerome Souers, acknowledges the crowd after the comeback win versus Eastern Washington. Photograph made with Nikon D610, Nikon 16-35mm f/4 VR at 30mm, f/4, ISO 5000, 1/1000-second. (Bill Ferris)

In hindsight, there are two lessons I took from this experience. The first is the importance of knowing the sport you’re shooting. Understanding the game and having the ability to anticipate what will happen next are critical to getting great photos. This is particularly true if you are limited to shooting with a relatively short focal length. (200mm is pretty short for football and other outdoor sports.) The second lesson is the value of choosing a location that allows you the opportunity to make a great photograph. Envision the scenario you would like to capture, go to the best spot for capturing that moment and allow the game to come to you. Of course, there is no guarantee things will play out as you want. That’s where your talent as a photographer comes into play. You’re there to document the event as it happens so, do your best with the cards you’re dealt.

Whatever your sport, whatever your photographic passion, today is a new day. It’s time to get out and shoot.

Bill Ferris | October 2014

Sports Photography

Wide angle zooms reach infinity focus within 2 to 3 meters, allowing you to freeze motion and achieve good depth of field even at the widest aperture. This image was shot at 16mm, f/4, ISO 4000, 1/500-second

Wide angle zooms reach infinity focus within 2 to 3 meters, allowing you to freeze motion and achieve good depth of field even at the widest aperture. This image was shot with a Nikon D600 full-frame DSLR using a Nikon 16-35mm wide angle zoom lens at 16mm, f/4, ISO 4000, 1/500-second. (Bill Ferris)

Sports and wildlife photography are extremely demanding of you, as a photographer, and your equipment. You are often shooting in low light, farther from your subject than you’d like–when it comes to wildlife, sometimes too close for comfort–and trying to capture a moving target. These are situations where your photographic technique and your equipment’s ability to make good images are pushed to the limit. In this blog entry, I’m going to focus on sports photography, offering some tips on how to capture compelling, dynamic images under challenging circumstances.

Battling for position beneath the basket. This image was captured at 70mm, f/2.8, ISO 2500, 1/800-second

Battling for position beneath the basket. This image was captured with a Nikon D600 and Tamron 70-200mm zoom lens at 70mm, f/2.8, ISO 2500, 1/800-second. (Bill Ferris)

Basketball is a sport which allows photographers to be relatively close access to the action. This doesn’t make the sport easy to shoot but it does make basketball easier to photograph than other sports. I used a Nikon D600 to capture all the images in this article. Sports photography is one area where a full-frame sensor, such as that in the D600, can give you an advantage over a digital camera with a smaller crop-sensor. The pixels on a full-frame sensor are larger than those on a crop-sensor DSLR body offering similar resolution. Larger pixels are more efficient. In other words, they do a better job of capturing light than smaller pixels. As a general rule, A full-frame DSLR will deliver at least a full stop of improved high ISO performance in comparison with a similar resolution crop-sensor body.

Why is this important for sports photography? If your objective is to capture a moment, your objective is often to freeze motion. (Please, note that freezing motion is not required for good sports photography. It is, however, a common practice.) To freeze motion, you need to take really short exposures, typically using shutter speeds between 1/500 and 1/1000 second. To make a good quality image at such fast shutter speeds, you’ll need two things: a fast lens and a camera with good high ISO performance. (Since flash photography is prohibited on the field or court, you’ll need to rely on your lenses and sensor to make the most of the available light.) Most sports photographers shoot with lenses offering fixed apertures of f/2.8 or faster. ISO settings are typically in the 1600 to 6400 range…sometimes faster.

In the above image, I was shooting at 70mm, f/2.8 using an ISO of 2500 and a 1/800-second exposure. If you zoom in to 100% on the full-size version of the image, you’ll see a slight touch of blur on NAU player’s right eye. Also, the reflected lights on his cornea are slightly elongated. Even shooting at 1/800-second, the image does not completely freeze the motion.

This image was taken with a Tamron 70-200mm zoom at 200mm, f/2.8, ISO 6400, 1/800-second

This image was taken with a Nikon D600 and Tamron 70-200mm zoom at 200mm, f/2.8, ISO 6400, 1/800-second. (Bill Ferris)

Another advantage of a full-frame sensor is its comparatively shallow depth of field. This advantage is due to the fact that crop-frame sensors effectively extend the focal length of a lens. Nikon’s DX format sensors have a 1.5X crop factor. In other words, any lens used on a DX format body will have an effective focal length 50% longer than it will on a full-frame or FX format Nikon body. The lens I used to take the above image was set to 70mm on my full-frame Nikon D600. On my crop-sensor D90, that same lens would have an effective focal length of 105mm and a correspondingly greater depth of field. The pleasing bokeh in the above image would not be as dramatic in images made with the D90. Objects in the distance would be more in focus, reducing the separation between the subject and the background.

This photograph was taken with a Tamron 70-200mm at 135mm, f/2.8, ISO 3600, 1/640-second

This photograph was taken with the Nikon D600 and a Tamron 70-200mm at 135mm, f/2.8, ISO 3600, 1/640-second. (Bill Ferris)

Here’s an image that does a nice job of freezing the action. If you zoom in to view the image at 100%, you’ll see the NAU player’s eyes are in focus. This is the number one rule of good photography: focus on your subject. When shooting basketball or another sport where the athlete’s face is in view, you should focus on the eyes. How do you know if you’ve succeeded? Look at a 100% view of the the eyes in the original image. If light reflected off the cornea is sharp and well-defined, the image is in focus. If the eye is soft or fuzzy, the image belongs in the recycle bin.

A technique I use to achieve good focus is called, Back Button Focus. Back Button Focus (BBF) moves the auto focus function of your DSLR from the shutter release button to the Auto Exposure Lock/Auto Focus Lock (AE-L/AF-L) button, typically found on the back of a DSLR body. Why do this? Most DSLR shutter release buttons allow you to activate auto focus with a half-depression of the shutter release button. To take a picture, depress this button fully to actuate the shutter. When shooting sports, there is an advantage to separating auto focus from shutter release.

Taken at 200mm, f/2.8, ISO 6400, 1/800-second

Taken at 200mm, f/2.8, ISO 6400, 1/800-second. (Bill Ferris)

In the above photo of NAU men’s basketball head coach, Jack Murphy, he was squatting while speaking to his team. The distance from him to my camera wasn’t changing. In that situation, I used the AE-L/AF-L button to set focus on his eyes, then waited for him to turn and face me before taking the exposure. If the Shutter release button also triggered the camera’s auto focus function, taking the picture may have reset focus on another person in the frame, ruining the picture.

Another advantage of moving auto focus to the AE-L/AF-L button is the potential to extend the battery life of your camera. If you shoot with vibration reduction (VR or VC) lenses, that half-depression of the shutter release button will activate the vibration reduction motors. The VR motors draw additional power from your camera’s battery. Using the AE-L/AF-L button for auto focus allows you to wait longer before engaging VR, which will extend your battery life.

200mm, f/2.8, ISO 5600, 1/800-second

D600 with Tamron 70-200 at 200mm, f/2.8, ISO 5600, 1/800-second. (Bill Ferris)

So, how do I set up my camera for a sports photo shoot? First, I put the camera in full Manual mode. Why? Well, I know there are two factors over which I want total control. The first, is aperture. I want to use my lens’s widest aperture. This maximizes the amount of light falling on the sensor, which allows me to make a good image using short, fast exposures. A wide open aperture also delivers images with beautiful bokeh, creating clear separation between the subject and surrounding environment. The second factor I want to control, is shutter speed. If I’m trying to freeze the action, I’ll choose an exposure of 1/500-second or faster. You’ll notice many of the images in this article were taken with exposures of 1/800-second.

Having selected the aperture and shutter speed, I will then engage a setting I rarely use: Auto ISO.  When doing landscape and portrait photography, I generally select a low native ISO setting of 100 or 200 to reduce noise in the resulting photograph and maximize image quality. Sports photography is one of those scenarios where you need to use–and trust–the camera’s high ISO capability. Selecting Auto ISO allows you to concentrate on framing, focus and when to push the shutter release button. You can choose to manually control ISO and, to be honest, many photographers are able to make ISO changes on the fly without missing a shot. Personally, I prefer to keep things simple and Auto ISO reduces the number of critical variables I have to monitor. Of course, this technique is only as good as your DSLR’s ability to meter and select a proper ISO.

D600 with Tamron 70-200mm at 200mm, f/2.8, ISO 5000, 1/800-second

D600 with Tamron 70-200mm at 200mm, f/2.8, ISO 5000, 1/800-second. (Bill Ferris)

With the manual settings in place, I’ll then double-check my camera’s auto focus setting. For landscapes and portraits, I use Nikon’s Auto Focus Single-Servo (AF-S) mode and choose a single auto focus point. In a nutshell, the AF-S mode tells the camera to set focus just once and lock that in place until the shutter is actuated. Landscapes don’t move and, in many portraiture settings, your subject is not moving. So, AF-S is a mode that allows you to precisely set and hold focus. Choosing one auto focus cross-point gives you further control over these critical factors.

Sports photography is a different animal, altogether. Since your subjects are moving, it’s generally better to select Auto Focus Continuous-Servo (AF-C) and a cluster of cross points where your subject is most likely to be within the frame. With AF-C selected, my D600 offers options of 9, 21 or 39 cross point clusters to predictively track and follow focus. This illustrates another advantage of assigning auto focus to the AE-L/AF-L button. With my right fore finger resting atop the shutter release button, my right thumb is able to depress and hold the AE-L/AF-L button to engage continuous auto focus. When I’m ready to take an exposure, I press the shutter release button.

D600 with Nikon 16-35mm at 16mm, f/4, ISO 5600, 1/640-second

D600 with Nikon 16-35mm at 16mm, f/4, ISO 5600, 1/640-second. (Bill Ferris)

Burst rate is another setting I’ll adjust prior to the game. Again contrasting sports photography with landscapes and portraiture, shooting constantly moving subjects is a scenario where your camera’s high speed burst rate is a real asset. Over the course of one or two seconds, a basketball player can go from the top of the key to leaping and finishing with a layup kissed off the glass or a monster dunk. My D600 has a maximum continuous burst rate of 5.5 frames per second. That’s one frame about every 0.2-second. If you have any doubt about how much can happen in two-tenths of a second, review a short burst sequence. In that collection of 5 to 10 images, there may be one where the player’s face is visible, the ball is visible, focus is pin sharp and framing is perfect. The other images may be soft in focus, poorly framed or have some object obscuring the subject’s face. I don’t recommend holding down the shutter release for seconds on end. But a well-timed, one-to-two second burst at your DSLR’s fastest rate can go a long way towards ensuring you get the shot.

Nikon D600 with Tamron 70-200mm at 200mm, f/2.8, ISO 6400, 1/800-second

Nikon D600 with Tamron 70-200mm at 200mm, f/2.8, ISO 6400, 1/800-second. (Bill Ferris)

Let’s talk about subject matter for a moment. Certainly, the primary objective of your photography will be to capture the critical moments and plays in the game. But sports are about more than just the action on the field or court. It’s also about what’s happening on the benches, in the stands and on the sidelines. The above image has nothing to do with the final score. But it captures a genuinely personal moment among the players on the Northern Arizona bench. If you didn’t attend the game, you probably don’t know what the final score was. However, seeing this image, may give you a clue. NAU dominated. They led by twenty or more points throughout the second half and won by that same margin. Hence, the players on that bench felt comfortable sharing a light moment–a bit of humor–before the final buzzer sounded.

200mm, f/2.8, ISO 4000, 1/800-second

200mm, f/2.8, ISO 4000, 1/800-second. (Bill Ferris)

Finally, I’ll share a few thoughts on lens selection. I brought three lenses to this shoot: Nikon 16-35mm, f/4; Tamron 24-70mm, f/2.8 and Tamron 70-200mm, f/2.8. All are zoom lenses with vibration reduction. The two Tamron lenses are fast, with fixed f/2.8 apertures throughout their zoom ranges. The Nikon 16-35mm is one stop slower at f/4, which would normally be a significant limitation in this setting. However, the excellent high ISO performance of the Nikon D600 body allowed me to freeze the action with this ultra-wide angle zoom.

Of the three, if I had to choose just one to bring to a basketball game, it would be the 24-70mm, f/2.8. It’s wide enough to frame players, head-to-toe, beneath the basket and long enough at the 70mm end to isolate a player from the waist up. The 70-200mm, f/2.8 would be next in my bag. The reach of this lens allows me to get up close and personal, filling the frame with the face of a coach or player. It also allows me to follow action on the far end of the court. In fact, if I were limited to just one lens for all sports shooting, it would be the 70-200, Sports like football, baseball and soccer are played on larger fields that demand a longer zoom range to bring the action closer to you, the photographer.

This photo was taken with a Nikon D600 and Tamron 70-200mm combo at 200mm, f/2.8, ISO 4500, 1/800-second

This photo was taken with a Nikon D600 and Tamron 70-200mm combo at 200mm, f/2.8, ISO 4500, 1/800-second. (Bill Ferris)

In summary, the key to successful sports photography is freezing the action. The tools that allow you to do this are a camera body with very good high ISO performance (advantage: full-frame sensor), fast lenses (f/2.8 or faster), and an auto focus system that accurately tracks and predicts focus on moving subjects. Shooting in manual allows you to control at least two critical settings: aperture and shutter speed. Using the camera’s Auto ISO feature can simplify things for you. Using your camera’s continuous auto focus setting and moving control over auto focus to the AE-L/AF-L button are an asset to achieving accurate focus. Focus on the eyes of your subject. If the eyes aren’t in focus, the image belongs in the recycle bin. When you’re ready to shoot, a well-timed short burst will help to ensure you get the shot. And finally, capture images that tell the full story of the event, including action around the court.

Now, get out and shoot!

Bill Ferris | November 2013