C. Fn-04

Ive been reading alot of threads lately about using custom function 4 to focus instead of the default half press. I read my XTi Manual but I dont really get how this is beneficial.

In option 1, when I press the * button, the camera focuses like it would when i half press, then i take the shot. It seems like the * button is used to focus instead of the half press

what exactly are the differences/benefits?

This custom function separate focus lock from exposure lock. This means that you can easily focus one part of the image and then lock exposure on another part. There are other advantages as well. This thread should help explain more:

https://photography-on-the.net/forum/showthre​ad.php?t=46965

Thanks, for anyone whos interested in this function and dosent want to read through those 15+ pages, this pretty much summed it up

ScottE wrote in post #472242
If you don't see any point to relegating autofocus to the * button, don't do it. Many of us find it the most functional way to use the camera.

Most of the time I have my camera set with autofocus on the * button and autofocus mode on AI Servo. That way I have an instant choice between AF modes. If I want One Shot, I just point the centre sensor at where I want autofocus to be and press the * button once. That locks focus on that point and I can recompose without worrying about holding the shutter half way down. If the subject starts to move, I can just hold the * button down and immediately I am in AI Servo mode. I also have manual focus immediately available at all times when using USM lenses by just not touching the * button and focusing manually. Again there is no inconvenience of having to hold the shutter half down while recomposing or waiting for the subject to show some emotion or for the light to be just right.

The only time I don't use AF on the * button is when I am taking sports shots in the winter when it is very cold. When the hands are cold and the gloves are thick it is sometimes difficult to coordinate the action of thumb on the * and index finger on the shutter.

Other than that I do not understand why anyone would use any other setup.

Perhaps people who have grown up with auto focus camera have different habits from us old geezers who spent most of our lives with manual focus.

Scott

Seems like I will be swtiching to 4-1, AI servo, and center point focusing for quite a while.
Out of curiosity, do you lose any sharpness if you recompose your image alot after the AF has already been locked?

mismis wrote in post #5137924
Thanks, for anyone whos interested in this function and dosent want to read through those 15+ pages, this pretty much summed it up


Seems like I will be swtiching to 4-1, AI servo, and center point focusing for quite a while.
Out of curiosity, do you lose any sharpness if you recompose your image alot after the AF has already been locked?

Focus recompose is a significant issue with shallow DOF, but if you have adequate DOF it's not so much of a problem.

When using this method, is there any point in using center point focus versus all points? Doesn't the AI servo start with the center point anyway? The advantage of all points is that if the target moves from certer, then it will be tracked by one of the other points. Is this correct?

'Perhaps people who have grown up with auto focus camera have different habits from us old geezers who spent most of our lives with manual focus'

Guess so, my first SLR was AF and so far I haven't noticed a problem with the 'usual' way. If I find a problem I will try the CF 04 thing to see if it fixes it, until then I will leave well alone.

Max F wrote in post #5140937
When using this method, is there any point in using center point focus versus all points? Doesn't the AI servo start with the center point anyway? The advantage of all points is that if the target moves from certer, then it will be tracked by one of the other points. Is this correct?

Yes that is the way I understand that it works. I use all points for shooting motorsports in AI Servo. My keeper rate is a little higher with all points.

I will never shoot with a shutter half-press for AF again. I just can't use it. Cfn 4 is the FIRST thing I change on any DSLR I own.

Problems it solves:
- Separates AF from the shutter, so if you have lenses with FTM (I will never buy a non-FTM lens), you never, ever have to switch to MF. Ever been in a situation where you achieved focus (say, on a tripod), and were waiting for the right moment to fire the shutter, realised that your lens would refocus if you pressed the shutter, so switched the lens to MF? This solves that.
- It's a lot easier to maintain control by pressing a separate button than half-press. I've accidentally released the shutter when I didn't want to in a moment of excitement whilst half-pressing. With half-press, I have to be more careful with the pressure I apply, with Cfn 4, I can press the focus button as hard as I want .
- When tracking or focusing, the key difference is that if you let go of the * button, you can fire the shutter without it refocusing. If you let go of the half-press, the next time you shoot again, the camera will refocus whether you want it to or not.
- I just LIKE separating controls onto separate buttons, it intuitively makes more sense to me.

Read the link Mark posted. Shutter half-press is, imho, the most idiotic thing ever and I'd never be able to use it again. * Focus takes some getting used to, but once you do, I reckon most people would never touch shutter half-press again.

Sometimes it is a good idea to read all the pages of a thread... rather than start a new thread.

perryge wrote in post #5141381
* Focus takes some getting used to, but once you do, I reckon most people would never touch shutter half-press again.

Couldn't have said it better myself. I have been trying to think of a situation where half press would be a better way to go, but I seriously can't. OH, WAIT!! Maybe when you hand your camera to someone else who wants to try it out and you don't want to be troubled with explaining how C.fn-04 works? Only then might be be usefull!

I as well will likely never use half press focus again.

Jethro790 wrote in post #5141437
Couldn't have said it better myself. I have been trying to think of a situation where half press would be a better way to go, but I seriously can't. OH, WAIT!! Maybe when you hand your camera to someone else who wants to try it out and you don't want to be troubled with explaining how C.fn-04 works? Only then might be be usefull!

I as well will likely never use half press focus again.

yea, everytime i hand my camera to someone to try it out or take a picture of me, the first thing i do is change the C.fn 4 back to its default.

and yea i cant stand using it the default way anymore.

DDan wrote in post #5141365
Yes that is the way I understand that it works. I use all points for shooting motorsports in AI Servo. My keeper rate is a little higher with all points.

is it like that on the XTi?? if so man i shouldve used all points then in basketball.

mizouse wrote in post #5142559
yea, everytime i hand my camera to someone to try it out or take a picture of me, the first thing i do is change the C.fn 4 back to its default.

and yea i cant stand using it the default way anymore.

Cfn 4 on 1 or 3 should BE the default.

mizouse wrote in post #5142577
is it like that on the XTi?? if so man i shouldve used all points then in basketball.

Yep. See page 58 of the manual. You might have problems with the camera picking up a subject other than the one you want with all of that activity though.

Perryge, thank you for your list of "problems it solves" I have read the other posts on this topic several times over the last week, but I didn't quite "get it". Somehow your explanation got through. I'm going to give it a try for a few weeks.