70-200 2.8 II Struggling with AI Servo

Hi there,
I'm having issues using my 70-200 II. I see shots taken with it of dogs running flat out that are as sharp as a tack. I take shots of my kids and my keeper rate is abysmal, and I'm pretty sure they can't move as quick as some of these dogs I'm seeing . I must be doing something wrong as shots I take of relatively motionless subjects are very crisp.

I need some thoughts please on where my technique is falling down. Here's a couple of crops from this weekend.

Taken at 1/500, f/2.8, ISO 400.

HTTP response: NOT FOUND | MIME changed to 'image/png'

HTTP response: NOT FOUND | MIME changed to 'image/png'

I'd like to check your EXIT but can't see your images. They appear for a few seconds then just go to a box with a red "x". Other threads seem to be OK.

On your issue, what metering method are you using and what camera? I have found (at least with my 60D) that AI Servo sometimes works better with spot or center weighted metering, particularly if the light level is marginal.

Could be your camera chose to focus on something else other than your kid.

The red square not necessarily means that's what the camera has focus on, especially on al servo mode and even in one shot mode.

little johny wrote in post #16864642
Could be your camera chose to focus on something else other than your kid.

The red square not necessarily means that's what the camera has focus on, especially on al servo mode and even in one shot mode.

I thought that it went, "it focused on something within the red square".
If the red encompasses(is larger than) the AF sensor, then the AF in these shots may be looking at something without any contrast whatsoever.

With servo mode there is no "I have locked signal", driver beware!?

Do you have the body set up for release priority, equal priority or focus priority?
If it's set for release (or equal) then the shot will (or can) be taken before focus is achieved.

Bob

Camera body is a 5DmkIII

John - Hmm, not sure what the metering mode was. I'll have to check. I usually post images to flickr then link, but with these 'helpme' images I use skitch to grab screen shots and use their link.

Canon Bob - Pretty sure it's on focus priority as I only want in focus shots, but I'll check when I get home in case something has changed.

Oh yeah, I was using focus priority 2. Kids were on their scooters coming straight towards me.

swoffa wrote in post #16865496
....Canon Bob - Pretty sure it's on focus priority as I only want in focus shots, but I'll check when I get home in case something has changed.

Check your AF2 menu (AIServo) and make sure the slider is to the right....page 95 in your user guide

Bob

little johny wrote in post #16864642
The red square not necessarily means that's what the camera has focus on, especially on al servo mode and even in one shot mode.

Assuming the shots above are from DPP, or similar software that can read the focus data, The red square shows the active focus point when the shot was taken.

You have it wrong way round, in AI servo it should be over what the camera was focusing on, as the camera is continuously focusing until the shutter is released. The only exception would be if you have the tracking parameters set to delay switching when the AF point wanders of onto another target, in which case the focus may not have caught up with the new position.

It is one shot mode that the red square is meaningless as that just shows the focus point in use when the focus was locked, as the camera could have moved around considerably with recomposing the square could now be over anything, not necessarily what was focused on.

To the OP, it is hard to try and diagnose what may be causing your issue without knowing what AF pattern you were using and what focusing parameters (or at least "case") you were using, as these can make a significant difference to how it tracks a moving subject.

Were you perhaps using Spot AF, the smaller area of the AF points? That can have more trouble finding enough contrast to work with in such a small area, and so that could slow down the AF. Spot AF needs care as it can be tricky to get a good contrast line in the right place.

I think metering patterns are a red herring, there is no connection between the AF tracking and the metering system.

sandpiper wrote in post #16865676
Assuming the shots above are from DPP, or similar software that can read the focus data, The red square shows the active focus point when the shot was taken.

Yes DPP

I mentioned 'focus priority 2' before, what I meant was AF Case 2(I have terminology issues)
AF point expansion was used in these shots (Bottom of p72 in manual), the 5 point variety.

Makes sense, I'll keep that in mind.

Anything else I can do to help you assist me?

Thanks for your feedback so far guys, it's appreciated.

What you need to do is look through your viewfinder and make sure that your subject appears in focus and then take the shot. Make sure you have set your diopter so the image when in focus is as sharp as it can be. Using a focusing square is a good guideline. You don't need to press the shutter, just look at the centre one and adjust the diopter.

There is no indication that focus has locked on in AI Servo. If you are using the centre focus point make sure that area is on your subject when tracking. Press the shutter half way and start to track. When AF locks on to your subject and it looks in focus press the shutter all the way. You have to trust the process.

Many people like to use the back focus button. Here you set the shutter button so it only actuates the shutter. You press the the back focus button with your thumb and track. When it locks press the shutter. If you continue to keep pressing the back focus button, continue tracking and you are locked on you can press the shutter as many times as you want or set the drive to high speed continuous.

I don't use the back focus button however I will give it a try again this summer. I trained myself to press the shutter half way. When I lock on I press the shutter all the way. When I release the shutter I only let it go up half way so AI Servo continues to track. As soon as you let the shutter up all the way AF tracking shuts off then your have to press half way and re-acquire focus lock again.

I would not get into the back focus button to start. Are you using single point focus? You should be for now. Set it up for centre point to start. Press the shutter half way and track. When your kid looks in focus press all the way. Even if you lose tracking by lifting the shutter after the exposure is not an issue. Practise tracking and locking on first to get your confidence up. Then you can start to experiment.

Thanks for the reply digital paradise.

I do in fact use back button focus (AF-ON) and have grown to love it. Just not with this lens and moving objects, which seems to be the opposite of what this lens seems to bring to the table.

Perhaps I'm just to hasty and am not letting it settle in to focus. I do have the body set to focus priority though, so my thinking is it shouldn't take the shot unless there is focus lock.

Hmm.

How does it do with shooting static objects in one-shot?

The first pic appears to be front focused....can't quite tell on the second one. What aperture were you shooting at?

swoffa wrote in post #16867912
Thanks for the reply digital paradise.

I do in fact use back button focus (AF-ON) and have grown to love it. Just not with this lens and moving objects, which seems to be the opposite of what this lens seems to bring to the table.

Perhaps I'm just to hasty and am not letting it settle in to focus. I do have the body set to focus priority though, so my thinking is it shouldn't take the shot unless there is focus lock.

Hmm.

No. It will let you shoot. I have shots of birds in flight where I got too hasty and pressed the shutter and the bird is completely OOF. Since you know about this it may be something else.

It will still fire even without a solid focus lock after it has hunted "long enough".

Keyan wrote in post #16868032
How does it do with shooting static objects in one-shot?

The first pic appears to be front focused....can't quite tell on the second one. What aperture were you shooting at?

That is really front focussed. If that is the case and it were my lens it would go to Canon. I don't that is it - hopefully.