AI Servo Experiences with 10D

[dsze]

Regardless of lens used, what has been your experiences using AI Servo on the 10D bodies?

....IF you like AI Servo on the 10D, do you AF with the shutter button or the * button?

-daniel

[PacAce]

If you ask me, it's not just a matter of whether or not to use AI Servo but also, if you do use AI Servo, how you select your focusing points. And, of course, the most important question is "What are you going to be shooting?" Obviously, a landscape shot is not going to required AI Servo. And shooting racing cars at the tracks may require a different strategy for selecting the AF points compared to, say, trying to track a bird in flight.

[dsze]

Good points Leo.

Yes, I am referring only to tracking moving subjects like athletes, animals or kids/pets moving around.

If you want to mention how you select your AF points, that would be good too. That is, do you keep it on center all the time, let the camera choose, or do you choose the point that is closest to the faces/eyes in your frame?

thanks,
-daniel

[CyberDyneSystems]

I voted at the top,.. but in hindsite it was after some practice...

Like Leo,.. there are some caveat associated.
I use AI servo with CF 4-1 (Focus with *)

Whether I am using a single focus point or using all 7 points and trying to take advantage of the cameras ability to track moving subjects depends entirely on the situation, subject size and speed, aperture used (DOF) and the of back ground (how "busy")

Here are some lessons learned.

If you don't have enough DOF then focus has to be too precise (ie: on a birds eye) for allowing the camera to chose focus point)

Predictive AF requires all 7 focus points. (9 on the 20D)

Tracking a moving subject with all focus points active is folly in front of a busy background.

If you have the DOF and the right background (and the right lens) predictive AF can really work!

On static or slow moving objects allways use a single focus point only.

I tend to try and use single focus point only under all conditions so I can get the right part in focus.

Using CF 4-1 press and hold the * button for a duration of time for accurate focus to "settle" in.

I find that a simple tap of the * button may only "start" to get a subject in focus,.. (sometimes it will look in focus in the viewfinder),. but if you are working too fast it may not be spot on yet.

The speed with which true sharp focus occurs varies dramatically from lens to lens..

[dsze]

Good advice CDS... Thank you.

[scottbergerphoto]

A little clarification of AI Servo is in order. By default, in AI Servo, all focusing points other then the center AF point are made inactive until focus is achieved. Only then, if you have limited your focus points to one, then that will be the one to follow the subject. There shouldn't be any difference in initial focus acquisition.

From Chuck Westfall of Canon, USA:
When your EOS camera is set for automatic focusing point selection (all focusing points active), the camera selects a focusing point for you. This setting behaves differently depending on whether you've selected One-Shot AF or AI Servo AF. When One-Shot AF is combined with automatic focusing point selection, the EOS evaluates all focusing points simultaneously and usually picks the closest readable subject. When AI Servo AF is combined with automatic focusing point selection, the EOS wants you to tell it which subject you are interested in tracking, so *at first* it shuts off the outer sensors and waits until you point the center focusing point at a readable subject. Once the camera has 'acquired' the subject, all other focusing points are activated and the AF system will track subject movement not only towards or away from the camera but also left to right, right to left, and up, down or diagonally across the picture area covered by the focusing points.
Excerpted from:
http://www.robgalbraith.com/ubbthreads/showflat.php?Cat=&Number=174243&page=&view=&sb=5&o=&fpart=all&vc=1
Also:
http://photonotes.org/other/ai-servo.html

[CyberDyneSystems]

Yes.. with AI servo and trying to chase a moving subject,.with all points activated,.. you are still trying to use the center focus point.. where the other 6 (or 8 or 44 on other cameras) points come in is in the "predictive tracking".

If the subject is defined well enough and the background is not too cluttered,. the 10D actually can do this remarkably well.. but you must have all points activated, and the cconditions have to be right.

Needless to say,. the 1D does it much better with 44 more points surrounding the center point...

[PacAce]

A little clarification of AI Servo is in order. By default, in AI Servo, all focusing points other then the center AF point are made inactive until focus is achieved. Only then, if you have limited your focus points to one, then that will be the one to follow the subject. There shouldn't be any difference in initial focus acquisition.

From Chuck Westfall of Canon, USA:
When your EOS camera is set for automatic focusing point selection (all focusing points active), the camera selects a focusing point for you. This setting behaves differently depending on whether you've selected One-Shot AF or AI Servo AF. When One-Shot AF is combined with automatic focusing point selection, the EOS evaluates all focusing points simultaneously and usually picks the closest readable subject. When AI Servo AF is combined with automatic focusing point selection, the EOS wants you to tell it which subject you are interested in tracking, so *at first* it shuts off the outer sensors and waits until you point the center focusing point at a readable subject. Once the camera has 'acquired' the subject, all other focusing points are activated and the AF system will track subject movement not only towards or away from the camera but also left to right, right to left, and up, down or diagonally across the picture area covered by the focusing points.
Excerpted from:
http://www.robgalbraith.com/ubbthreads/showflat.php?Cat=&Number=174243&page=&view=&sb=5&o=&fpart=all&vc=1
Also:
http://photonotes.org/other/ai-servo.html
Scott, if you are implying that whether you are using auto AF point selection or manual AF point selection in AI Servo mode, all AF points are initially deactivated except for the middle one, and then once the middle one has achieved focus, the manually selected AF point then becomes active, then I'll have to take exception to that. The center AF point is active wth all the other AF points being deactivated only when you are in auto AF point selection.

If I misread your post and that's not what you were saying, then accept my apology. :)

[CyberDyneSystems]

Oh.. no I'm not reading that.
if you are implying that whether you are using auto AF point selection or manual AF point selection in AI Servo mode, all AF points are initially deactivated except for the middle one, and then once the middle one has achieved focus, the manually selected AF point then becomes active, then I'll have to take exception to that

And I agree that is not the case ... I use AI Servo with single AF points OTHER than the center point all the time.

I read it to mean only when using -all 7 AF points- (or camera selects AF point) that the starting AF point is allways center.

And yet now re-reading it.. I see that the first paragragh certainly does read that way??

Hmm... Essentially every performance I shoot I use an off center AF point on the dancers/models face. (camera turned portrait,. AF point either one or two points above center chosen)

That one AF point allways lights to indicate focus.. however,. the center AF point is pretty much 99.9% of the time going to end up on the dancers center of mass in this situation.. so it may very well be starting there and ending up on the selected off center AF point over the dancers face??

************************************************** ******
I just tested this with my 20D (here at work with me) and it definitely starts AF at the slected AF point.. not the center.

[PacAce]

Oh.. no I'm not reading that.


And I agree that is not the case ... I use AI Servo with single AF points OTHER than the center point all the time.

I read it to mean only when using -all 7 AF points- (or camera selects AF point) that the starting AF point is allways center.

And yet now re-reading it.. I see that the first paragragh certainly does read that way??

Hmm... Essentially every performance I shoot I use an off center AF point on the dancers/models face. (camera turned portrait,. AF point either one or two points above center chosen)

That one AF point allways lights to indicate focus.. however,. the center AF point is pretty much 99.9% of the time going to end up on the dancers center of mass in this situation.. so it may very well be starting there and ending up on the selected off center AF point over the dancers face??

************************************************** ******
I just tested this with my 20D (here at work with me) and it definitely starts AF at the slected AF point.. not the center.
Which first paragraph are you referring to?

[Todd Jacobsen]

I use AI servo for capturing parachute landings at my DZ. I utilize the opposite of CyberDyne and choose the lowest point in portrait in order to capture the individual and his/her canopy - as they fly by me.

AI servo works great in this instance.

[scottbergerphoto]

My post only makes sense if you are talking about auto AF point selection. If you select a single manually selected AF point to use in AI Servo then that is the only sensor that will be available to track your subject. You can't have a single manually selected AF point to start and then have the rest kick in. If you want the other sensors to be available to track your subject, you must use auto AF point selection.
From the same post by Chuck Westfall:
"The choice between automatic focusing point selection and manual focusing point selection is an either/or proposition. There is no way to combine the features of each mode. When the camera is set for manual focusing point selection, there is no way for focusing points other than the manually selected individual focusing point to be active. When the camera is set for automatic focusing point selection, there is no direct way for the user to control which focusing point the camera will choose, other than as described in my earlier reply. "

[dsze]

All makes very good sense. Thanks. For some reason I'm still having trouble getting what I would consider enough sharp images with AI servo, using all 7 AF points OR Manually selecting 1. It gets close and the photos could probably be used, but are soft and would require some serious PS'ing. I've always been a 1-shot AF guy manually selecting my AF point, so maybe I just need more practice with AI Servo... I'm actually finding that I get fewer sharp images by using the * button as well. I would like to keep using the * as I see the many benefits, but for some reason I'm getting fewer 'perfectly' focused images.

-daniel

[scottbergerphoto]

All makes very good sense. Thanks. For some reason I'm still having trouble getting what I would consider enough sharp images with AI servo, using all 7 AF points OR Manually selecting 1. It gets close and the photos could probably be used, but are soft and would require some serious PS'ing. I've always been a 1-shot AF guy manually selecting my AF point, so maybe I just need more practice with AI Servo... I'm actually finding that I get fewer sharp images by using the * button as well. I would like to keep using the * as I see the many benefits, but for some reason I'm getting fewer 'perfectly' focused images.

-daniel
I used to get alot of soft images with AI servo until I realized that I needed to get my shutter speed up. I now routinely shoot things that move, at 1,000 sec and faster, and I get alot more keepers. It also helps to familiarize yourself with the subject and anticipate how they will move. Pre focusing helps as well. I use CFn. 4-1 most of the time unless I'm using a cable release.

[dsze]

Thanks Scott.... I considered the shutter speed issue and bumped up my ISO so that I could keep my aperture and bump up the shutter speed, but I didn't bump it up NEARLY that much! I'm shooting at 1/400 and below I'd say. If it quits raining today I'll try to get out and get my shutter up closer to 1/1000 if possible. So, are you thinking that some of my softness is subject movement? It surely wouldn't be camera shake alone at 1/400, but maybe my shaky hand at the long end of my 70-200 combined with subject movement is causing the blur, not incorrect focus?

thanks,
daniel

[Cadwell]

I can't see it being down to shutter speed. Even head on I shoot race cars at 1/320th (sometimes 1/400th if they're REALLY fast) and I don't suffer from softness when using AI servo.

The trick I find is to allow the mechanism to settle. That means tracking the subject for at least half a second keeping the focus point locked at a constant point on the subject before firing the shutter.

[scottbergerphoto]

I'm probably a little older then you youngins and have a little of that benign essential tremor thing. All I can tell you is that with a long lens, I guess I should have noted that before (400-500mm), for me, shutter speed is king.

[Jim_T]

I use AI servo mostly for capturing birds in flight. I find it isn't 100%. Some images come out blurry and out of focus.. I find about 75% good and 25% bad rather than the 50-50 selection you have in the poll..

[PaulB]

I'm with Cadwell on this one for motorsport.
You HAVE to let the AF settle on the target befoe pressing the release all the way.
I use the centre point mostly, others if the composition demands it, with the shutter release doing all the work - can't get my head round the * button for focus on action shots, two things to do instead of one! Making it as easy as possible is my aim.......And as for all points active? Well I have used this for predictive AF with success but still find that I'm happier with the centre AF point only.

[KennyG]

Allowing the AF to settle is key to getting the shot on focus, on any of the Canon bodies, not just the 10D. My old 10D is in use by one of our members here and AI Servo seems to work as well for him as it did for me.

For motorsport we work with shutter speeds generally no higher than 1/400, even for GP cars, and AI Servo is a must. It is probably one of the first camera features we come to grips with.

Paul, you going to BSB? I have my media ticket but I won't be going as I will be at Oulton and Knockhill. She left it far too late to let us know.

[PaulB]

Hi Ken,
Sorry we won't be seeing you this weekend at the Croft BSB.
Guess what Tony's bought? - delivered tomorrow (he hopes!). I shall be using it too if I can get it out of his hands.....

[BigRed450]

I"ll agree with Kenny that adequate pre-shot tracking is essential. I use only the center AF point and the * button for focus in order to have AE lock separate from AF/AF Lock.

[22littlereasons]

Many years ago, before AI servo, sports or action photography was far more difficult than it is now. Even if AI servo isn't effective on every shot, it certainly increases the odds in your favour than manually focussing ever did.

[KennyG]

Hi Ken,
Sorry we won't be seeing you this weekend at the Croft BSB.
Guess what Tony's bought? - delivered tomorrow (he hopes!). I shall be using it too if I can get it out of his hands.....

Let me guess, a 500? Great for bikes.