7D Action Focus Questions

Just got the 7D earlier this week and have been practicing. Been especially working on the actions shots and am struggling to get really sharp images. Is the following statement correct when it comes to getting sharp action shots:
Camera needs fast shutter speed, a fairly small aperture (don't want a narrow dof), zone point expansion, AI Servo, good light, fairly fast focusing lens, and skill/practice. Have I missed anything that would get my keeper rate high? It seems that I keep missing focus on my moving subject and I hope it's just a lack of skill on my part. I've attached a photo. Maybe this is sharp and I'm expecting too much?
Thanks for any tips,
Randall
Exif info:7D & Tamron (signature line), 5.6, 1/500, AE, ISO 1000 (cloudy day), focal length 282, AI Servo, Auto Point Expansion, High Speed Continuous
Also, I did some sharpening in DPP and Photoshop.

It looks pretty sharp to me. The bricks in that wall under the dog look sharp also. When you focus on the dog when it's stationary how sharp is it? I used to have that model lens and it would front focus a bit. (Not saying yours is.) If you look at the dog with a 100% crop how sharp do the details look?

it looks like it locked focus on the bricks.
try bumping the focus just before you shoot.

Back Button Focus would help.

Looks pretty sharp. I think you have most of the typical settings right. The only other one I'd recommend is to slow down the AI servo tracking speed a bit. The default setting is a bit twitchy and may track off if you dont keep the AF point on the subject continuously or something passes in front of it.

Thanks for the replies.
Stationary is really sharp (very nice).
When you say bump the focus I assume you mean release the button and refocus?
I may try the back button to see if this helps.
Thanks again for the tips.
Randall

Here is a good tutorial on setting some of the custom functions for better tracking of fast moving targets.

http://www.garyluhm.ne​t/bio/tips_0310

Lenses make the biggest difference. I don't know anything about the Tamron, but the 18-55 is a non-USM lens, with slower, less accurate focus.

I'd use Single AF Point... rather than Expansion. That would keep the camera from focusing on other things. Have you looked at the image in Zoombrowser or Canon DPP to see what AF point was active?

For your shot above, If you wanted it completely sharp and frozen in mid air, you might have bumped up ISO to 1600 and gotten a higher shutter speed, too. 1/500 is marginal to stop all movement, that close to your subject. I image there is some motion blur if you look more closely. I can see some on the dog's right rear leg, in particular.

This is the second time in two days I've heard someone refer to "bumping focus"... Never heard it before and I've been using Canon AF cameras for over ten years.

I never "bump focus". It makes no sense to me to stop AI Servo, then force it to reacquire. I don't see any reason to do that. Instead I lock onto a moving subject and work to track it in AI Servo. Get on the subject early, track for a while, take your shot and keep tracking in case you want to take additional shots. It's almost like a golf swing or a baseball or tennis swing... followthrough is almost as important as the initial swing and moment you "strike".

Yes, I use Back Button Focusing. That helps, too.

Reducing AI Servo sensitivity a bit mostly works when you have obstructions and distractions to deal with... It keeps the camera from jumping to another subject too quickly. It's probably more important when using one of the multi-point modes (Expansion, Zone, All Points) than with Single Point mode. I think it might help when you are new to the camera, too. Try setting Custom Function III-1 one step toward "Slow". This seems counter-intuitive... you want the AF to be as fast as possible, don't you? Actually what this is doing is slowing the camera from jumping too quickly to another point of focus, in case you let the AF point slip off your primary subject momentarily or you have an obstruction pass between you and the subject briefly.

After using a pair of 7Ds for a couple years now, for a bit over 100,000 shots total, I have changed this back to one step toward "Fast". I think it effects AI Servo following when a subject changes direction, too... something I often have to deal with. If you have this setting slowed a little, one or two frames might miss focus when the subject abruptlly changes direction. But, it seems to work best for folks who are new to the camera.

vorlon1 wrote in post #14310509
Here is a good tutorial on setting some of the custom functions for better tracking of fast moving targets.

http://www.garyluhm.ne​t/bio/tips_0310

That doesn't seem to link to anything...

Sorry about that. Here is the corrected one.

http://www.garyluhm.ne​t/bio/tips_0310.html

@ Amfoto: Thanks for the tips!
@ Vorlon: Thanks for the link!
Lots of good info. from both.
Randall

Note that back button focus executes exactly the same thing as keeping the shutter button halfway down. It's just a more convenient way of doing it, but it adds nothing to camera AF performance. Provided you hold the buttons at the same moments, of course.

Single point or single point with expansion is usually the better ways for action situations. Zone AF or all points AF can be useful, but only under very special circumstances. Definitely not for a dog in a picture like the one above.

Bumping focus has a value if the camera has found something far off to focus on. It may not want to re-acquire on the right target by itself, especially if the AF speed is set to slow. If you let go of the focus button, then press again, it will re-acquire as fast as the camera is able to, then continue according to the setting for AF speed (really AF refocusing delay).

Keeping the focus button pressed for at least half a second before shooting an image like the jumping dog also gives the camera a chance to track the subject and figure out that it starts moving, when the dog jumps, in time.

Finally, keeping the focus point on the moving target is of course essential, and that's where more than one point can come into play in a useful way, depending upon the target.

Thanks Anders.

I use the 7D primarily for wildlife photography, and most of that would qualify as "action" photography---lots of birds in flight, for example.

Your picture is not at all bad! I second a lot of what's been said, and I'd emphasize a faster shutter speed (that's key) and turning off expansion---using just the center AF point. (The latter will irritate some people, but it's what works for me. Try to get better at aiming with your lens and take as much control as possible away from your camera, which, after all, can't tell the difference between a dog and a brick.) The slower servo will help too, but I don't think that was a factor here.

The other trick to getting good action shots is, frankly, "spray and pray." Get the exposure right, set your camera to continuous burst, hi-speed, keep AF on servo and just hold the button down, taking as many shots as you can of the action in question. (The 7D has a good buffer, so you should be able to get a bunch.) This will dramatically increase the odds of you getting at least one shot that's sharp. (Even the pros will tell you they get far more bad than good---it's the nature of the game.) No film being wasted, so why not shoot away?

As for aperture (DoF), there's no hard-and-fast rule here. I use the 400 5.6L, which is sharp wide open at f/5.6, and I tend to keep it there, occasionally stopping to f/8 if the light is really really good. 5.6 isn't that shallow, really, and while it's true that a tighter aperture would be a bit more forgiving when it comes to depth and focus, I personally prefer to keep the aperture as wide as possible and avoid having to bump the ISO (causing grainier pics). If I had, say, the 400 f/2.8 (someday!), I might consider stopping down to 5.6 for closer subjects where I'd be afraid the DoF would be too shallow, but with a lens using a 5.6 maximum ap, I don't think there's really any need to stop down--unless the lens is noticeably sharper at, say, f/8. Again, a fast shutter speed and good focusing technique are the most important things!

@noahcomet: Thanks, all good tips.
Randall