AI-Servo and 7D

I was trying to shoot my niece at her cheerleading competition this past weekend. After I loaded the photos on my computer, I noticed that the AI-Servo tracking on my 7D misses pretty badly; so I must be doing something wrong and/or I have something set wrong. By "missed pretty badly" I mean it focuses on her and then the next frame focuses on the background, then back to her, as she is moving.

What settings in the 7D should I check? Any C.Fn settings? What technique should I be doing? Maybe me holding down the shutter button and following her with the center group of focus points is not the thing to do. ISO at 5000, 50/1.4 lens at f/2.8 with a shutter at 1/320 and drive set to 8 fps. Please help. All advice greatly appreciated. This is my first time shooting a cheerleading competition.

I would choose centre point assist, and change the C-Fn to slow on tracking so it is less keen on picking up something else if you drift off target.

artyman wrote in post #11796972
I would choose centre point assist, and change the C-Fn to slow on tracking so it is less keen on picking up something else if you drift off target.

Especially the second part here; dialing the tracking sensitivity back to slow will really help with that. It's one of the biggest things I like about the 7D.

You will always have missed shots but yeah, to increase your keeper rate you need to do what artyman said and slow down the tracking. This means the camera will give you more time to get the AF point back on target before it selects something else to focus on. It's C.Fn III-1 for that function.

You could also check C.Fn III-3. If this is set to mode 0, then focus will jump away from your active AF point and switch to the main point if a closer subject enters the frame. Setting this to mode 1 will stop that from happening, as tracking priority will be given to the current subject.

It's probably worth looking at C.Fn III-2 in the manual as well, and making the choice you think best suits your shooting goal.

I don't know if it's something you want to try out, but in addition to the things mentioned, maybe give back button focus a try. I have found in shooting sports that it is easier with AI Servo to keep the back button pushed to track the subject versus keeping the shutter half-pressed. Just a thought.

Below is a link regarding shooting for volleyball......should be similar for cheerleading. I have been using similar settings for a while and my keeper rate has definitely increased (ignore the second comment by va_rider about the AF tracking speed to fast.....it should be slow)

https://photography-on-the.net/forum/showthre​ad.php?t=982086

+1 on "yourdoingitwrong" comments about back focus button. I find that focusing with the sensistive shutter button makes me a little more shaky....concentrating on only holding it halfway down while tracking.....much easier to just hold the * button in.

I stand by my response... I leave the AF tracking to fast... works like a charm...

Please expand on that va_rider. I don't mind being put in my place but would like the OP to get an explanation to help him make the decision (since it's his thread). Thanks.

Newby, here's my reasoning... I shoot college sports for a newspaper, and I shoot motorcycle track photography.... let's say you have AF set to slow... you're tracking your subject ... let's say in basketball.... they run towards the basket, take a shot... you squeeze the shutter.. pop a few quick shots... everything is good... now.. next play, Player A has the ball... running down the court towards you.. heading down the edge of the 3 point line.. you're about to squeeze the shutter, and the ball gets tossed cross-court to player B who, with a quick charge, runs and dunks. You miss the shot as the AF is trying to change from 12' in front of you to 25' to the left as you try to track, recompose, and zoom...

Slow AF is good if you're following one player or one racer at the track... let's say you're shooting your own kid... or a buddy at the track... if you're trying to take in a whole event... I'd leave the AF tracking at fast... it's made the difference between getting a shot and missing a shot plenty of times for me.

Sure... if you aren't good at pointing the camera at what you're shooting... the AF will jump, and you'll be shooting between players at a set of empty bleachers... but, if you can track your subject... the AF will stay right on.

Specifically to the OP... I'm willing to say that 50mm is too short to be shooting cheerleading... even if you're standing next to the judge's tables... at 50mm, the center focal point is taking in a big chunk of real estate trying to focus... I'm willing to bet that at a reasonable distance, the cheerleader is maybe a third of the area of the center focal point... so, the focus is trying to lock on something that's not filling the focal point, which will lead to jumping back and forth as it's trying to make sense of the differences of depth in the focal point. ...


but... post a few samples..

^^Seems like some sound reasoning there.

Using the slower sensitivity, though, you can just quickly re-engage focus at the new point by letting up on the focus button and re-pressing it while you're changing target. More so when combined with back button focusing, but not impossible with the default setup.

The other thing that idea takes into account, which sounds like the OP is not doing, is that you're using a single, specified AF point. They sound to be using zone AF, which is still enough of an auto mode that it can decide, at any time, to grab whatever IT feels is the best contrast object under the available AF points. So "fast" is likely to exacerbate that issue in a crowded scene, I'd think.

Back button focusing takes a bit of practice to get used to it, but I would have it no other way now. I have a lot of difficulty maintaining a half-press on the shutter button -- heck, I have a difficult time even finding the shutter button because of its lack of being ergonomics -- I can't even feel the the slight bump that it makes and am constantly taking the camera from my eye to see where my index finger is relative to the shutter button.

Like Ken said earlier, use single point AF. If you use zone AF or auto select AF with a "busy" background, the focus is likely to jump around especially if it finds something with higher contrast or something closer to the camera. Manually following the subject with the center point may take more work, but it is better for you to be in control than the camera.

Thanks for the comments va_rider...and your explanation definitely makes sense if the shooter is an experienced 7D photographer.
However, in this case, the OP was missing the focus point. The priority in this case should be getting a usable pic....one that is in focus...not just one taken at the right time (and perhaps not really in focus).

My undestanding is:
1. AF set to fast - priority is to focus on the new subject right away (even if the focus is not ideal)
2. AF set to slow - priority is to have the best focus on that subject (even if you don't get the shot at that split second....since the autofocus will try until the best focus has been achieved).

Surely if the OP is missing the focus point it would be to his advantage to slow the speed to obtain the best focus on the preferred subject?

I can only speak from my experinces since getting my 7D. I have been shooting my kid playing soccer. The first week I had the speed at neutral....the second week fast.....and lately slow. I find that the setting on slow has worked best for me.....

Newby2Cam wrote in post #11798144
...
My undestanding is:
1. AF set to fast - priority is to focus on the new subject right away (even if the focus is not ideal)
2. AF set to slow - priority is to have the best focus on that subject (even if you don't get the shot at that split second....since the autofocus will try until the best focus has been achieved).
...

You've got your custom functions mixed up a little bit.

C.FnIII.1:

1. Slow: Camera will wait a time before switching subject if your focus point strays off the subject
   
2. Fast: Camera will switch immediately to a new subject if the focus point strays from the original subject

1. 0: AF/Tracking - First priority for the camera is getting good AF when the button is initially activated, second priority is maintaining tracking while the AF button is held. Will sacrifice shooting (drive) speed in order to maintain these.
   
2. 1: AF/Drive speed - First priority is good AF when the button is initially activated, second priority is keeping shooting speed as high as possible while the shutter button is held. May not track as effectively to keep these up.
   
3. 2: (shutter)Release/Drive speed - First priority is activating the shutter as soon as the shutter release is triggered, second priority is maintaining shooting (drive) speed as long as the shutter release is held. Will sacrifice AF accuracy and tracking time to maintain these items.
   
4. 3: (shutter)Release/Track​ing - First priority is activating the shutter as soon as the shutter release is triggered, second priority is tracking accuracy. Will sacrifice shooting (drive) speed in order to maintain these.