Canon 5d mark iii AF

So I just got the 5d3, and I'm trying to make sense of the AF system. 61 points. Cross points. 15 points. Just trying to get an idea of how to set this up for use underwater. My initial reaction is to just make all 61 points active and start shooting. What are you guys doing?

That would be the wrong thing to do. Set up the camera to single AF point then use the joystick to move the point around to where you want the focus to be. Activating all 61 points gives up that control and the camera could lock on to something that you don't want.

S.

Thanks for the reply. What abou all those different pre set AF cases and adjusting tracking sensitivity, accel/deceleration, etc. there's just a lot there that I'm not used to, and making adjustments on the fly while underwater can be challenging...

I leave mine in setting 1. You're not tracking flying birds or race cars. If the subject is slow moving, set to One Shot, if it's moving, i.e. a shark swimming towards you, set to AI Servo. I use the Setting 1 to shoot birds in flight, so a fish is not a problem for the Mk3.

I'm probably making this more complicated than necessary...

Not really. You you are shooting fish like a flasher wrasse, the programs can make or break the shot. I use Case 5 for that and also turn tracking sensitivity down so it doesn't acquire another fish swimming in front of the camera.

The 5D3 does a great job of locking on a subject, and with sensitivity off, it doesn't lose subjects easily at all.

I also use case 1 without issues.. for moving subjects Al Servo, never tried Case 5.. I will try that next week to see the behavior..

Just a note: The 61 point of focus depends on the lens you are using, not all are enabled for every lenses. You can find that information on the manual, so there is a list of lenses separated by group with the enabled points for each one.