I have a Canon 7D with the latest firmware v2.0. For the longest time, I've shot in AV mode with fixed ISO (sports + BIF) and let the camera adjust the correct shutter speed (usually around 1/1500s). After nearly 10K shots, I got really mixed results especially in a long sequence of continuous AI Servo shots. More often than not, 30% of shots in the sequence are blurred while pictures just before and right after are in focus, even though ZoomBrowser showed the focus dead center on the target. I use Canon 70-200 IS USM MK2 and I have tried setting AV wide open (f2.8) as well as f4 and f5.6 with similar blur results in the sequence. This inconsistency drove me nuts!

Recently, though, for the first time I switched to using the M + Auto ISO mode and, boy, my keeper rate went up! Now, in a sequence of 10 shots, maybe I see one shot a little soft but the rest are in focus. I also got great results using my rather slow Canon 100-400L lens, too! So, a couple of questions for those experienced sports + BIF shooter out there:

1. Can those 7D shooters confirm my finding, or is it just my 7D unable to adjust the shutter speed correctly in a continuous AI servo shooting?

2. I'd much rather control the ISO, so I'd want to go back to using AV + fixed ISO mode. I'm thinking of getting a 1D MK4. Would I still need to use M + Auto ISO on 1D body to get consistent results in AI Servo mode?

Thanks for all your comments.

Gone: My first question is what kind of a scenario are you shooting in where you would expect drastic changes in the free-to-change camera setting? What you've described implies that whatever settings you are using, you are experiencing significant changes to shutter speed or ISO in the course of a sequence of shots. Unless your shutter speed is falling to a slow enough setting that you are experiencing motion blur, it is difficult to understand why one of the options you've asked about would be better than another. Capturing and maintaining focus throughout a sequence of shots should have much more to do with the AF system and settings, and your technique, than whether you are in auto-ISO or AV mode. Perhaps some sample photos would be helpful here.

Agreed with Russ... AF performance and tracking have nothing to do with the camera's exposure settings. Something else is at play here.

I shoot action Sports & Motorsports..

I use my 7D & 100-400 exclusivley.

I use, TV mode, & pick the SS I want, let it work the App to suit, I set my ISO @ 160 or 320...
If its variable light I set ISO to Auto , but set the max .
Centrepoint Focus , or occaissionally when shooting Aerobatic RC Helicopters Ill use Expended centre point,
AI Servo exclusivley

Here are my thoughts:

1. The camera will always focus wide open regardless of what you have the aperature set at. The lens will stop down when the shutter opens. That takes out and any aperature issues.

2. +1 to Russ & Paul They are the "Yoda" here... Listen and heed their knowledge!

3. My $.02 worth.... When I shoot sports, I shoot in AV mode or manual. Your aperature has the most effect on how your image looks (Think bokeh...)and how your subject is separated from the background; or what you want your background to look like. Now think shutter speed and set your ISO to get the shutter speed you need to stop the action or blur the action to achieve the desired results. If you're shooting in TV mode (unless your panning) your f stop could be foating all over the place.

4. I really can't remember the last time I've EVER used TV, P or Auto ISO.... I just can't risk letting the camera decide how my image should look. Wait, I can remenber the last time..... It was with my SD980 point and shoot on vacation.....

My thoughts for the OP.

1. Example and exif of sample would be helpful of the bad and good from a series
2. Custom functions give you a choice for the first shot in Servo multi shot in that you can choose whether you prioritize Focus, or the Shiuter release. Similarly you can separately choose whether Tracking or Drive Speed (I think but going from memroy on this second pair) is prioritized. I choose Focus and Tracking as the two that I prioritize.
3. The red AF square in DPP showing where the focus point was is not 100% accurate in that it is actually smaller Thant the real AF point in the AF system. I suggest you check you OOF images and see if focus was on some object around the red AF square.
4. Tack lock speed in custom settings. Shooting in Servo tracking with single point requires you to keep the AF point on you Subject. The track speed determines how fast the system will reacquire AF on the new object when you slip off the main subject or if something steps in front etc.
5. Another choice in Custom settings is the prioritize tin of either the Focus Point or Continuous Tracking. Choose continuous tracking.
(by the way, upon the v2 firmware upgrade on the 7d, my custome settings regarding the AF etc were reset I think, or Canon reset them when they fixed the power circuit)
7. When you say out of focus, can you confirm that there is some other areas or focal plain in the image that is sharpest? Otherwise you may have lens motion, stabilization unsettling, of non acquired focus, etc.

Let us know how you make out.

Guy

I think I'm understanding where the OP is coming from, however I don't have an answer for him.

Say there is a shaded area on a baseball field, maybe by one of the bases. however, as the base runner moves from one base to another, the light increases or decreases a considerable amount. If a player is running from 2nd to 3rd base, 2nd base is in the sun, 3rd is in the shade, the camera is going to compensate the shutter speed greatly if set in aperture priority. when the player starts at 2nd, the SS is 1/800 @ 2.8 ISO 100. As he runs to third, he enters the shaded area and the camera adjusts the shutter speed, SS becomes 1/400 @ 2.8 ISO 100. At 1/400, the runners limbs will have plenty of motion blur, but at 1/800 the player would be mostly frozen.

Same situation, Auto ISO this time. The player starts running, the SS and aperture are manually set this time, so when the player starts at 2nd, the SS is 1/800 @ 2.8 ISO 100. When the player enters the shaded area, the camera now bumps the ISO rather than slowing down the shutter speed. SS is still 1/800 @ 2.8 but the ISO is now 200.

In this situation, the keeper rate would increase using auto iso in manual exposure mode, rather than manual iso and aperture in aperture priority mode.

Gonemad: when you mentioned "30% of shots in the sequence are blurred while pictures just before and right after are in focus, even though ZoomBrowser showed the focus dead center on the target" I think you're referring to motion blur rather than an oof subject. If your shutter speed is all over the place, some of the shots in the sequence you took may have motion blur rather than being out of focus.

I used auto ISO on my MKIV Friday night at the local H/S football game and it worked great. As the night wore on I switched back and forth from manual to auto and got good results in both cases.
Manual ISO seems to be better for when the light comes and the light (dark) is constant.

Thanks everyone for chiming in. For the sake of time, I won't address each and every comment, but here are the top 2 category of comments that I'll address:

1. Motion blur vs OOF subject. I went back to the picture sequence and I did find the subject under the focus square was out of focus, rather than motion blur, because the grass behind the player was in focus. Incidentally, most of the OOF were sequences where the player is running towards the camera. I have no problem tracking a player while panning left/right. So, somehow, the 7D algorithm didn't detect the subject was moving towards the camera in AV mode. When I switched to M + Auto ISO (fixed f2.8 and 1/1000s), I was able to take great shots of players running towards the camera! I'm at a loss...

2. Camera settings: center with expansion, focus priority, -1 tracking sensitivity, AI servo, 8 fps, AV mode, f2.8/f4/f5.6

I'd upload a few examples.. that makes no sense to me what so ever.

Gonemad wrote:

2. Camera settings: center with expansion, focus priority, -1 tracking sensitivity, AI servo, 8 fps, AV mode, f2.8/f4/f5.6


It's possible that the DOF is changing as the aperture swings from 2.8 to 5.6, revealing less than perfect focus/tracking.

So, after reading lots of articles about the Canon 7D autofocus sensor, here's one reviewer who experienced the same AF "backfocus" when the subject is running towards the camera:

"The percentage of OOF shots (they tend to be focused behind the direction the subject is traveling) I experience with the 7D is higher than I experience with the 1-Series bodies. Said another way, if your living depends on your ability to capture action quickly moving toward or away from your camera, I recommend that you get a Canon 1-Series body..."

For the complete article, refer to:
http://www.the-digital-picture.com/Reviews/Canon-EOS-7D-Digital-SLR-Camera-Review.aspx

Again, for the record, I only experienced this OOF "backfocus" when in AV mode, where the plane of focus is behind the player running towards my camera. I can't explain, and perhaps I need to re-experiment a bit more, why I get more in-focus when using M + Auto ISO (fixed aperture and fixed shutter). Sorry guys, I thought about uploading pictures, but decided against it for privacy reasons (under age girls).

Sounds like this is a tracking problem only. Therefore, I suggest changing two custom functions until you figure out your best hit rate. I believe it varies person to person as an individuals ability / technique impact these settings.

Change between Main AF Point Tracking and Continuous tracking.

Move the sensitivity from -1 to + 1 and see if there is an appreciable difference. Of course the +1 sensitivity won't "hang on" to the subject as long if an obstruction enters the field of view. However, it will be more responsive in jumping back on the intended subject and tracking slight movements.

Gonemad,
Forget about the article. Plenty of us track just find in multile mode with the photos to prov it. I remember one series with an F1 racecar coming at him with each one in focus. Use some of the advice on this thread to dial in you camera.

Guy

Alright, it took me a while but I think I finally understand how the Tracking Sensitivity (slow...fast), AF Expansion and Tracking Method (main/continuous) works which greatly impacts the keepers. So, please disregard my previous claim that Auto-Iso was giving me more keepers, that's because I also changed these various tracking settings as well. Thanks all!