Leaky Waders

I photographed a high school football game with a Nikon 7000D, Nikon 70-200 2.8 VRII lens. A colleague was using a Canon EOS 7D with a comparable lens. He posted his photos to a public site which included the exif data from each photo.

When I compare our photos I notice that at f2.8 my DOF is shallow and at the same f-stop his DOF is deep. I cannot understand why his DOF is so different than mine at similar settings.

The photo I have attached can be used as a comparison to those of my colleague. The settings of my camera for this shot were a focal length of 70, ISO 1100, shutter speed 1/500 and f2.8.

To view my colleague's photos please go to the following site:
http://sths.fotki.com/athletics/football/varsity/varsity-vs-strake-0/varsity-vs-strake-379.html#media

Exif data for his photo can be viewed from the site.

Thanks in advance for your feedback.

(Download)

oldtigger Loc: Roanoke Virginia-USA

there is a whole lot of shakin goin on in your shot.
May not be a DOF issue.

watchcow Loc: Moore, Oklahoma

Did you have your VR on while on a tripod or monopod? That can rob you of some sharpness. Looks like your friend's shot was taken with much higher ISO to get a comparable shutter speed, so I guess that was later in the evening. I am guessing it is just technique. Your image does seem to have some motion blur in it that it more noticeable farther from the camera. my inclination would be to use a tripod, and a wired release to isolate impulsive movements from the camera. Also make sure you are on the concrete lower levels of the stadium or have the camera support on solid ground. metal or wooden bleachers introduce and assortment of vibrations that VR can't account for.

mcveed Loc: Kelowna, British Columbia (between trips)

Your friend was shooting with a focal length of 95mm as compared to your 105mm so his DOF should have been somewhat deeper than yours. This alone wouldn't account for the apparent difference in DOF in these two images, however the distance from camera to subject (focus distance) would. He was obviously further from his subject than you were by a considerable margin. Remember DOF is a function of lens focal length, aperture and distance to subject.

Linda From Maine Loc: Yakima, Washington

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mcveed Loc: Kelowna, British Columbia (between trips)

Thanks, Linda. I saw that when I went for another look and amended my post.

Linda From Maine Loc: Yakima, Washington

For an example of the importance of distance to subject in figuring DOF: using an online calculator, if OP stood 20 feet away, dof is less than 3 feet. If friend was 75 feet from subject, dof is 20 feet. Just examples; I have no idea of the actual distances in these two shots :)

DOF calculator:

http://www.dofmaster.com/dofjs.html

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

You were closer to your subject, and your crop factor is slightly less - so taking the two things together, even though your focal length is a little shorter, your DOF at that distance is shallower than his. This assumes that both cameras are focusing where they are supposed to be focusing, not in front or behind.

Leaky Waders

That may very well be. My colleague is in his mid 20s and I'm im my mid 50's. He was hand holding with VR on and I was on a monopod with VR off. I figured since I was shooting with a monopod at a shutter speed of 1/500 the VR would not make a difference.

Leaky Waders

My VR was off, lens foot was attached to monopod. We were both shooting from the sideline of the field made of artificial turf. I have looked at almost all of my colleague's album of several hundred photos and they are all shot at iso 3500, f 2.8 and shutter of 1/400. I use the back button focus technique and try and follow the play as I shoot bursts of photos. I think my technique accounts for the motion blur. I'll try different techniques until I notice consistently sharp photos. Thanks for you input.

LoneRangeFinder Loc: Left field

This is the relevant post with respect to DOF & the comparison of your image with your friend's image....

Forget about VR... for now....

SonyA580 Loc: FL in the winter & MN in the summer

Tony Northrup (.com) has a U Tube comparison between Sigma, Canon & Nikon 70-200 f/2.8 lenses in which he claims the Nikon actually only goes to 140mm. I'm wondering how this might affect DOF, etc., on Nikon lenses.

Apaflo Loc: Anchorage, Alaska

That is at closer focusing distances.

The Nikon 70-200mm f/2.8G VRII has greater "focus breathing" than the others. At 20 feet, for example, if all of those are set to the longest focal length, the Nikon will have the widest field of view (shortest focal length), the greatest DOF, and incidentally the best image quality too (the primary effect of the Nikon design that causes greater focus breathing).

SharpShooter Loc: NorCal

Leaky, What Tony Northup is talking about is Focus Breathing which the Nikon lens desperately suffers from. The breathing problems are greater as you focus closer. So It's hard to say how much of what you are experiencing is from actual breathing.
The actual uTubes is worth watching, especially the part about the 70-200 zooms. But you'll also need to read some article on what focus breathing is.
Unfortunately not all lenses are created equal!
The only way to solve your dilemma might be to use your friends equipment. :lol:
SS

Apaflo Loc: Anchorage, Alaska

Not all Internet reviews are created equal either. The referenced review is not particularly a good one. It tells half the story and uses very poor photographic technique as the reasoning for an invalid conclusion!

The Nikon 70-200mm f/2.8G VR II lens uses a more agressive design for the floating elements that are moved during focusing. Like all of the 70-200mm f/2.8 lenses from Nikon, Canon, Sigma, and Tamron, it is an "internal focus" design, and they all exhibit "focus breathing".

The Nikon design has greater focus breathing than the others and as a result it has the best image quality at the minimum focus distance (MFD).

Tony Northrup uses a technique that is commonly called "zoom with your feet" to deride the Nikon's benefits. He is relating the perspective of an image to the focal length, which is a very poor way to work. Perspective is selected by choosing the right location to give the desired angle and distance from the camera to the subject. Only after that is done should a focal length be selected that will allow the captured image to be properly cropped to provide the desired framing. Perspective is typically a very precise requirement (that does not involve the equipment used), while framing need not be as precise and involves both the focal length of the lens and the pixel count of the camera's sensor.

Northrup should have compared his Canon image to the Nikon image cropped to the same pixel count as the Canon image. He can get exactly the same perspective, and with higher quality. Northrup used poor technique to cause an effect that he incorrectly blamed on equipment, and then failed to mention that the same equipment "cause" has the real benefit of higher quality image from the Nikon lens.