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Old Jul 1, 2010, 9:11 AM   #1
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Default AI Focus or AI Servo?

Hi all I was wondering if you could give me some advice on what I should set my focusing to.

I've got to shoot a charity fashion show and I'm torn between AI Focus or AI Servo on my 5D mark ii
I'm going to be at the end of the runway and the models will be pausing briefly facing my way, someone else is going to take care of what happens before they get to me

Do you think this is suitable for AI Focus?, I like the lock on I get from this method and should they move (hopefully focusing will track this)

Or... should I stick with AI Servo?

Cheers

James
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Old Jul 1, 2010, 9:56 AM   #2
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Are you capturing them when stopped or still moving? I would never ever choose AI Focus, it is letting the camera decide too much. If you are tracking them down the runway then AI Servo, it when they stop Single Shot AF. If you are concerned how short a time they will be still for then leave it with AI Servo and choose an AF point which is on the face and leave it there. Take a few shots as there might be a slight focus error at one point and you should be fine.

Another option which I use is to enable focus only on the rear AF button so you can lock focus where you want to and still take multiple shots without it changing.
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Old Jul 1, 2010, 10:04 AM   #3
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Are you capturing them when stopped or still moving? I would never ever choose AI Focus, it is letting the camera decide too much. If you are tracking them down the runway then AI Servo, it when they stop Single Shot AF. If you are concerned how short a time they will be still for then leave it with AI Servo and choose an AF point which is on the face and leave it there. Take a few shots as there might be a slight focus error at one point and you should be fine.

Another option which I use is to enable focus only on the rear AF button so you can lock focus where you want to and still take multiple shots without it changing.

Hi Mark, thanks for replying.

I'm banking on the brief pose to capture my shots, when they walk down the runway the first place they stop is about 3 mtrs in front of me for a couple of seconds.


you mention the AF button on the back, what do you mean 'enable focus only'?

I do sometime use this button, and have read a lot of photographers only use this to focus, what benefits does this give over the shutter?

sorry for asking more questions, only had the 5dii for a couple of months and only been taking pictures a year.
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Old Jul 1, 2010, 10:14 AM   #4
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No worries. I knew there was a reason I'd left my camera on the table rather than putting it away after the honeymoon, makes it easier to tell you where to look.

If you go to Custom functions 4 and then the first option which is Operation/Others and Shutter button/AF-ON button, then you will see that currently you should be on 0. If you switch to 3 this will turn off focus from the shutter release so you only focus with the rear button. This now means you choose when to focus and when to shoot as the two functions are separate now. This could be helpful in that you can pick a point and leave it focused there or have the focus all the time (remember I said to do this with AI Servo in your case) when you are tracking them move. Once they stop you can stop focusing, recompose and still have the focus correct even if there is no focus point over them.

This could be too complex, if so then just shoot portrait orientation and select the AF point that covers the face and with AI Servo keep focusing and take multiple shots.

What lens/flash will you be using?
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Old Jul 1, 2010, 10:23 AM   #5
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That was my next question (should i select all or one focus point..haha) thanks

I will be using a 580exii, and its a tie between my 50mm 1.4 and rely on the 21mp abilty to crop the photos and which will/should illiminate the need to fire the flash or... my 70-200 F/4L,which can be darn slow and will need higher ISO's and or flash ( I wish i had the 2.8IS :-(
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Old Jul 1, 2010, 10:43 AM   #6
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The 70-200mm f2.8 is a nice lens, after my 24-105 it is probably my most used... hmmm or possibly the 85mm f1.8, but probably you can get away with the f4 in that environment, get there early and take test shots. ISO 3200 is not an issue for the mkII and I never have to even break a sweat thinking about using it or not. Even 6400 can clean up pretty nice in RAW if you need to push it. As long as flash is allowed (it should be, then a lot of your problems go away regarding lighting, assuming the temperature of the lighting of the catwalk matches OK.
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Old Jul 1, 2010, 11:04 AM   #7
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The 70-200mm f2.8 is a nice lens, after my 24-105 it is probably my most used... hmmm or possibly the 85mm f1.8, but probably you can get away with the f4 in that environment, get there early and take test shots. ISO 3200 is not an issue for the mkII and I never have to even break a sweat thinking about using it or not. Even 6400 can clean up pretty nice in RAW if you need to push it. As long as flash is allowed (it should be, then a lot of your problems go away regarding lighting, assuming the temperature of the lighting of the catwalk matches OK.
Thanks for your help Mark, I too don't have A problem with shooting hi ISo on the 5D, I shot the Festival of the lion king show at Disney with my F/4 70-200 at ISO12-800 , and with the help of noiseware pro, got some amazing shots.

I want the 24-105 myself, I borrowed one for a Bday party and the results, using a gold onmi bounce were nothing short of lush.

at the moment I only have a 17-40, 70-200, 50mm 1.4 and 105mm macro.

I'm looking forward to the show tonight, its not everyday you get to photograph a lingerie fashion show...

Will let you know how i get on.
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Old Jul 1, 2010, 12:09 PM   #8
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Thanks for your help Mark, I too don't have A problem with shooting hi ISo on the 5D, I shot the Festival of the lion king show at Disney with my F/4 70-200 at ISO12-800 , and with the help of noiseware pro, got some amazing shots.

I want the 24-105 myself, I borrowed one for a Bday party and the results, using a gold onmi bounce were nothing short of lush.

at the moment I only have a 17-40, 70-200, 50mm 1.4 and 105mm macro.

I'm looking forward to the show tonight, its not everyday you get to photograph a lingerie fashion show...

Will let you know how i get on.
Make sure you share some of the photos with us as well!!
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Old Jul 8, 2010, 9:53 AM   #9
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Thanks Mark, I ended up using AI Servo in part 1 and AI Focus in the second half.

both yielded more or less the same amount of keepers, and it was the less experienced models that seemed to supply the non keepers... So I'll blame them.

Will get a few samples up at some point.

thanks for your help

James
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Old Jul 10, 2010, 1:26 PM   #10
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Originally Posted by Mark1616 View Post
No worries. I knew there was a reason I'd left my camera on the table rather than putting it away after the honeymoon, makes it easier to tell you where to look.

If you go to Custom functions 4 and then the first option which is Operation/Others and Shutter button/AF-ON button, then you will see that currently you should be on 0. If you switch to 3 this will turn off focus from the shutter release so you only focus with the rear button. This now means you choose when to focus and when to shoot as the two functions are separate now. This could be helpful in that you can pick a point and leave it focused there or have the focus all the time (remember I said to do this with AI Servo in your case) when you are tracking them move. Once they stop you can stop focusing, recompose and still have the focus correct even if there is no focus point over them.

This could be too complex, if so then just shoot portrait orientation and select the AF point that covers the face and with AI Servo keep focusing and take multiple shots.

What lens/flash will you be using?
Sorry to bring this back, but Mark, Why would you choose option 3 over option 2. Is the continouse metering the problem?
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