Help with AI focus or, not sure??

[johneric8]

I have a question, I have been using my quick finger to get action for the most part with a steady eye. But, recently I have been challenged with some different situations where I need a sharp picture. For example: If I'm taking pictures of a bride and groom that are walking toword me from about 20 yards away is it best to be in AI focus with my 20D ? I would love to be able to fire away in this situation but i'm not sure how. I got two great shots in this situation but would have like to have gotten more. I pretty much had the camera in auto focus and locked and snapped. But I found I was having to wait too long and I'm sure I missed at least 6 or 7 more good chances in those 10 seconds of photo oppurtunities. So basically what is the best mode to be in when you are shooting a moving subject coming toword you from quite a bit of distance?:)

Blessings

[tim]

AI servo is ideal for subjects moving at a reasonably constant speed, so yes, it should be fine for that.

[Schumi]

AI servo is ideal for subjects moving at a reasonably constant speed, so yes, it should be fine for that.

Soo for objects moving fast like F1 cars, would it be better with AI focus? I am going to SPA this year and need some hints/tips to get some good captures :)

[muscleflex]

no - AI Servo!

[CorruptedPhotographer]

Definitely use AI Servo

[David1943]

Soo for objects moving fast like F1 cars, would it be better with AI focus? I am going to SPA this year and need some hints/tips to get some good captures :)
For fast objects like cars or motorbikes coming towards you, either use AI Servo or pre-focus on a point where you want to take the picture and wait until the moving object gets to it.

Happy snapping, David :)

[Schumi]

Thanks for the tips everyone :)

[dsze]

Practice with AI servo awhile before relying on it in a situation like a wedding. Its not as flawless as it sounds. See this threadHERE (http://photography-on-the.net/forum/showthread.php?t=76861&highlight=Servo+poll)

-daniel

[new2DSLR]

Has anyone had experience with AI-Focus (where the camera decides whether it should be "one-shot" or "servo")? Is it smart enough to decipher the correct situation most of the time.

I usually choose "one-shot" or "ai-servo" because Ithink that the camera's AI is not that "smart".

[Little Fish]

Maybe I have this wrong but this is what I gather from the manual:

If you are in one-shot AF you can press the shutter down halfway and get your focus and exposure reading and then you can recompose the photo without having the settings change which is really handy.

If you are in AI Servo AF then your focus and exposure change if you try to recompose the photo with the shutter pressed down half way.

With AI Focus you start out in one-shot mode so you can recompose the photo without the settings changing as long as the subject doesn't move but if the subject moves the camera refocuses so you don't miss the shot.

No option is correct for all situations but I like to use AI Focus because I shoot a lot of photos where there is very little depth of field and I'm often using a specific AF Point to focus, therefore I find myself needing to recompose after I focus on a specific object.

Frank.

[mblanton]

If I were shooting a wedding and wanting to capture the bride and groom walking down the isle I would do it one of two ways. 1. Switch to manual and pre-focus on the spot you want capture the bride and groom (give yourself plenty DOF) and make your exposure when they walk by. 2. Use AI Focus in AV mode and give yourself lots of DOF (but lighting may be a problem in this situation.

Mike

[new2DSLR]

Maybe I have this wrong but this is what I gather from the manual:

With AI Focus you start out in one-shot mode so you can recompose the photo without the settings changing as long as the subject doesn't move but if the subject moves the camera refocuses so you don't miss the shot.

Frank.

Hmmm...can the camera tell whether the camera moved or the subject moved? This is why I'm afraid to trust the camera's AI for "AI-Focus".

[robertwgross]

Hmmm...can the camera tell whether the camera moved or the subject moved? This is why I'm afraid to trust the camera's AI for "AI-Focus".

You, as the operator, can remove one of those two from the equation. Use a tripod.

---Bob Gross---