Tips for getting the best auto-focus

Started Dec 25, 2012 | Discussions thread
MAC Forum Pro • Posts: 13,825
Re: Tips for getting the best auto-focus

yes Yogi, I've used C.Fn 6, #1 - "AE Lock/AF" for the last decade

besides enabling Zone Focus by simply removing your thumb from the back button, to lock focus on a zone and let the subject come into the zone and then shoot, there is a very important use of this feature that I'll also explain below.

I photograph events "in a pj environment" where people are sometimes rather still but then move in a moments notice. If you are in single shot, you'll miss the moving moments -- not even time taking a few seconds to switch to AIServo.

The C.Fn 6,1 feature enables you to better stay in AISERVO ALL the time while photographing pj events -- because you can simply lock focus on still life by removing your thumb, and if the still people start walking or running, you are already in AISERVO where you need to be to track - you are ready to track in an instant.

Since my 10d days I developed the "nervous habit technique" of staying in AISERVO and punching the back button on still life (a good contrasty edge) and listening if the focus moves on the third punch -- so the first punch is to get close, the second punch is refine, and the third punch is to listen for any kind of movement of the focus system in the lens - and if not, remove thumb to lock focus, recompose and shoot. Modification to this is --that in very low light I found it best to punch once instead on 3 times since the focus can hunt more in very low light

I have a 95% + hit rate with prosumer dslr cameras for the last decade using this technique in AISERVO most of the time and using the back button to focus lock and focus track.


all I can say is to practice

Y0GI wrote:

MAC wrote:

Y0GI wrote:

MAC wrote:

Y0GI wrote:

I found this tutorial over on the 10D-7D forum. It is very good and has a lot of useful information for beginners. If your photos are not coming out sharp, get out of Automatic Mode and give these tips a try!

To do zone focus by locking focus using the manual lens switch is lame.

just use custom functions to use back button.

when you removed your thumb from the back button the focus locks. I can't imagine his method to loose the plane of focus as he reaches over for the switch.

Agreed. 'Zone focusing' and BBF are prolly going to be above the heads of most beginners.

If you have a good tutorial on BBF for Rebels, please share!

yeah, it takes some getting use to.

settings are in custom functions.

and he summarizes it with the goalie example

That is a good explanation of BBF. I thought that I'd follow that with one example of how to do BBF on the T4i/650D.

To enable BBF, go into the camera's Custom Functions. See C Fn IV: "Operation/Others" and select option #6 "Shutter/AE Lock". Page 197 of the T4i/650D manual is reproduced here:

Page #197: T4i/650D User's Manual

The desired option for enabling BBF is #1: "AE Lock/AF". This will set the shutter to "AE Lock" and the "*" button to "AF". Then, to take the picture, you will first press the * button with your thumb and then press the shutter button when ready to take the shot. In this way, you will have separated the two functions of Auto Exposure Lock and Auto Focus.

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