Where can I find advice on using an advanced AF system for wildlife and bird photography?

Question

I recently purchased a Canon 7D, as my previous 450D had become a severely limiting factor in my endeavors to wildlife and bird photography (particularly bird photography, which I LOVE, but for which I have a bare handful of keepers out a few thousand shots.) The AF system of the 450D had a single cross-type point and a total of nine, while the 7D has a much more advanced 19 point system, all of which are cross-type. I've taken the 7D out a few times since I first purchased it, and while I have definitely had better luck photographing wildlife, I am still having trouble photographing birds on the move.

I have read through the 7D manual, however I am still not exactly sure where to start on learning how to use an advanced AF system in the real world for moving subjects. I could really use some insight from photographers who regularly use advanced AF systems for tracking subjects and keeping them in focus. I would also like to know how to take multiple shots of a subject on the move and keep them in focus between shots. While I can often nail one shot in a motion sequence, I regularly seem to fail to get proceeding or trailing shots after the one keeper (and that keeper is often not the most interesting one of the bunch.) The 7D supports a variety of AF modes as well, including AF Expansion and Zone AF, where the camera can supposedly utilize extra points around the selected point in case the subject moves away from the selected points area of sensitivity, or the selected point lands on a low-contrast part of the subject and a neighboring point lands on an area of high contrast (so focus can always be achieved, even if the selected point isn't detecting anything to focus on.) I have also not had much luck using either of these modes, and I think its primarily because I simply don't know how.

From a lens standpoint, I have used the following lenses:

• EF 100-400mm f/4.5-5.6 L
• EF 100mm f/2.8 Macro
• EF 50mm f/1.4

My most frequently used lens is the 100-400, usually at the 400 end, so aperture is only f/5.6. I am not sure if that might be a problem or not (as far as I understand, the 7D supports AF at f/5.6, although I am not sure how many points might be considered "high precision" at that aperture.)

Asked by jrista

Answer

There are several custom function options available to the 7D which can be configured to assist with tracking moving objects:

• C.FnIII -1 AI Servo Tracking Sensitivity You want this set to "Slow" - this will stop the AF system trying to refocus on anything that briefly passes between you and the subject you are tracking - handy with birds where branches etc might flash by as you track

• C.FnIII -2 AI Servo 1st/2nd Image Priority This should be set to 0 so that the camera will give priority to focusing on the subject over taking shots - basically, if it thinks it hasn't got a lock, it won't shoot while it obtains one

• C.FnIII -3 AI Servo AF Tracking Method Set this to 1 - this further adds to the system ignoring obstacles by allowing the system to use AF points around the main focus point when something gets in the way of what you were tracking

Use single point AF with the AF Expansion custom function (C.FnIII -6) switched on - this gives you accuracy on the initial pick up but then allows the camera to help out as you track.

These settings should be correct from the camera side of things but the story doesn't end here.

Your 100-400mm L lens has a 2 mode IS system, with more predictable objects, you should use mode 2.

For tracking moving subjects it is important to get a good solid stance and to track the subject as it approaches some time before you want to start shooting (trickier with birds but achievable depending on the behaviour of the species). You should also follow through after you shoot (much like when shooting a shotgun).

You need your feet about shoulder width apart and need to be facing across the path of travel of the object you're tracking:

Object -------------------------------------------->

               ^ 
              You 

Hold the camera with your right hand as normal and with your hand a good way down the lens (similar to holding a rifle or shotgun). Keep your elbows tucked in, possibly resting against your torso to provide extra support and twist your torso from the hips upwards to meet what you want to track. Track it in the viewfinder, ideally if you can switch eyes so if you're tracking right to left, look through the viewfinder with your left eye so you can keep your right eye open to help keep track of the object (especially if it moves erratically) - do the opposite for left to right.

Start tracking the object, and smoothly pan with it. If you are shooting birds, turning off IS altogether is probably a good idea as the movement is likely to be too erratic for the IS to keep up with (even in panning mode 2) - aircraft are steady enough to use IS mode 2 with usually.

Squeeze the shutter release, don't press it (just like with a rifle) or it will jolt the camera and try to keep the object in the viewfinder as you get glances between shutter releases. Carry on tracking as the object moves away.

Getting a smooth torso twist is paramount and takes practice but getting the stance right gives you the foundations to build upon.

Answered by JamWheel

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