AI Servo: How do you use it?

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Preeb wrote in post #14692290
The easiest way for me is to use the back button for focus. That way I can leave the camera in AI Servo and get the best of both worlds. Press and release the button when aimed at the subject to lock focus - hold the button down to track a moving subject. That way there is only one button to worry about, no changing modes back and forth, and exposure can be isolated to the shutter half press.

This above on all my Canon's unless I'm shooting a static object on a tripod like a macro subject or landscape. In those instances I use one shot AF.

How close were you to the stage? As someone mentioned, the servo mode is predictive and assumes that the target is moving either to or away from you at a constant velocity. Unless you're in row A, I don't see how you're going to get a constant z velocity that matters much or lasts long enough. If you were far enough away from the stage so that the guitarist was small, he might have been too small to allow the focus point to grab focus. Also, if he was moving left or right, he might have moved away from your focus point and the camera then reacquired focus on whatever was behind him. Honestly, it would not occur to me to use AI servo in a concert because of all these factors.

A good deal of misinformation here. And poor assumptions. For example, the OP said he's using a 70-300 zoom. Someone responded by saying something about stopping it down and not shooting "wide - open" - That lens will only shoot "wide open" at the short end of it's focal range.

Other info about back button focusing is also either misinformation or communication is poor. This doesn't surprise me since I think I've read more wrong info regarding BBF than any other single subject.

Read the owner's manual. If that doesn't make things clear, Canon's telephone tech support is very good and part of what you pay for when you buy a Canon EOS camera. Why ask for what seems like "guesses" here when you can directly ask someone trained in the use of your specific camera?

???

Delija wrote in post #14696982
A good deal of misinformation here...That lens will only shoot "wide open" at the short end of it's focal range.

Talk about misinformation.

I've never heard of a lens that will only shoot wide open, unless the aperture diaphram is stuck, in which case I'd send it for repair.

Neither the manual nor calling Canon would be of much avail.

rrblint wrote in post #14697056
Talk about misinformation.

I've never heard of a lens that will only shoot wide open, unless the aperture diaphram is stuck, in which case I'd send it for repair.

Neither the manual nor calling Canon would be of much avail.

"CAN" only be used "wide open" at the short end - Better?

It's a variable aperture lens -

Did your read what I wrote? Or just want to argue?

TheRightLight wrote in post #14692188
You hover the AF point over what you desire to be in-focus, and you then proceed to take the picture. Servo mode obviously acts much differently.

Your thoughts? Suggestions??
(My equipment: 60D, 70-300 IS USM.)

With AI Servo it is very important to keep the AF point glued to the point on the subject you want in focus. "Hovering" will not cut it! It's an art, but take heart, it can be learnt.

However, AI Servo is really meant for things like racing cars or bikes, things that are moving, but moving in a way that the cameras computer can work out and predict where the subject will be when the shutter opens. Random moves by actors or musicians on stage are simply too unpredictable.

Delija wrote in post #14696982
A good deal of misinformation here. And poor assumptions. For example, the OP said he's using a 70-300 zoom. Someone responded by saying something about stopping it down and not shooting "wide - open" - That lens will only shoot "wide open" at the short end of it's focal range.

The lens can shoot wide open at all focal lengths. What aperture constitutes wide open will vary with focal length. That is, after all, why its called a variable aperture lens. Stopping down the lens to increase depth of field was good advice.

Care to share with us what you think constitutes proper BBF setup and use?

Here are some visual examples to help this thread along. All of these are RAW files straight out of the camera.

Shot One with Servo AF enabled:

IMAGE LINK: http://imageshack.us …ages/401/0240af​point.png/

IMAGE LINK: http://imageshack.us …ages/844/024010​0crop.png/

IMAGE LINK: http://imageshack.us …s/845/0240alt10​0crop.png/

IMAGE LINK: http://imageshack.us …ges/696/0240met​adata.png/

Shot Two with One-Shot AF enabled:
(This is clearly under-exposed, but despite that, it *still* appears quite a bit sharper.)

IMAGE LINK: http://imageshack.us …ages/269/0687af​point.png/

IMAGE LINK: http://imageshack.us …mages/84/068710​0crop.png/

IMAGE LINK: http://imageshack.us …ges/835/0687met​adata.png/

Obviously, my 60D and 70-300 are capable of good results. That second shot is *plenty* sharp, especially considering the fact that I've done no processing on it at all and it's RAW.
The first shot, however, is pretty soft. With careful sharpening, I may be able to salvage it, but I'm quite disappointed in the IQ, and I think Servo may have something to do with it...

Thoughts?

Hmm...

I did notice that the first image was taken at f/5 as opposed to f/8 for the second. However, you wouldn't think that would make such a big difference... Right?

TheRightLight wrote in post #14699815
Hmm...

I did notice that the first image was taken at f/5 as opposed to f/8 for the second. However, you wouldn't think that would make such a big difference... Right?

I have owned this lens for a long time, and despite what some others might say, it simply works better stopped down a bit from maximum aperture.

At 70mm about f6.3 or f7.1

At 150mm about f7.1 or f8

At 300mm about f8 or f9(I even occasionally use f1o to f11)

It also seems to be sharper in the 130mm to 210mm range as well.

Given all of this, your first shot is a little soft looking...I don't know what happened.

Possibly the musician simply moved after you focused.

Perhaps the system simply failed in this shot...It's not perfect.

I find that I usually get about a 75%-80% keeper rate with this lens.

rrblint wrote in post #14699890
I have owned this lens for a long time, and despite what some others might say, it simply works better stopped down a bit from maximum aperture.

At 70mm about f6.3 or f7.1

At 150mm about f7.1 or f8

At 300mm about f8 or f9(I even occasionally use f1o to f11)

It also seems to be sharper in the 130mm to 210mm range as well.

Given all of this, your first shot is a little soft looking...I don't know what happened.

Possibly the musician simply moved after you focused.

Perhaps the system simply failed in this shot...It's not perfect.

I find that I usually get about a 75%-80% keeper rate with this lens.

My theory is that Servo is at fault.
Look: There *has* to be a difference between One Shot and Servo. If there was none, then why have two different modes?

As another poster suggested earlier, I'm beginning to think that Servo is only suitable for predictable motion. Anything else, and its a game of chance...

Looking through my other Servo shots, its clear something is amiss: My keeper rate is under 50%.

Wow. I'm so incredibly frustrated with myself right now. This is extremely disappointing.