How to recompose while the focus is locked on the subject?

[snowshine]

My Canon 40D.

I find my camera fail to lock on the subject that I have focused on and kept the shutter release button half pressed while attempting to re-compose the scene. When ever I move away from the focused object while the shutter button half pressed, I still hear the camera lens focusing noise.

I looked under the Menu->C.Fn III -2
It is set for
0: AF stop.

Now I turned the above setting to
1: AF start
But has no difference when I focus on a subject and keep the shutter button half pressed to recompose my scene, the camera lens makes a focusing noise,I presume to focus on the new subject in the scene!!

Can some-one help me to get it working so that I could lock my focus. {I am not after locking my exposure by the way}

Regards

[benm]

I looked at the manual on-line. Some of the most obtuse descriptions I have read in a while. From what I could comprehend the C.Fn III-2 function needs to have the button on the back of the camera pressed, labeled AF-ON. You could also try C.Fn IV-1 as that describes some AF lock functions. But I could not be sure of anything without actually testing it out on the camera.

[DavidGee]

Hi Snowshine,
Have a read of this article about Back Button Focusing . I know a number of people who now use this technique. Once you have got used to it you will never go back to the default way of focusing.

http://www.usa.canon.com/dlc/control...286&fromTips=1

David

[carregwen]

Snowshine

I think the function you need is C.Fn IV - 1. (it details it in the link that David posted) I just tried it on my 50D and it does work. I suppose it's better in certain situations - depends what you shoot most. Easy enough to change, I suppose.

[Donald]

I would also agree with the article that David has referred to. I have my 40D set for 'back button focusing' and certainly wouldn't want to change. I find it works easily for me in relation to focusing and then recomposing.

ps - Should add that I have also flipped the functions of the AE and AF buttons (again as referred to in the article) because once I went on to 'back button' I just found it 'worked' better. With my eye locked onto the viewfinder I found that my thumb automatically alighted on AE more easily than on AF.

Also, I find back button a better way to focus when I'm not using manual focusing (which is usually the case) with Liveview.

[snowshine]

Hello all,
Absolutely wonderful.
It has worked. I set it to C.Fn IV -1.
But soon set it to C.Fn IV -2 and get use to use the back button for focus as proposed here.
Donald is correct in I also find my thumb reach for *button while looking through my view finder. But this is my beginning to use in such manner. Soon teach my thumb to reach the correct button or follow as Donold's suggestion

I started to worry if my Canon 40D was faulty!!
Thank you very much guys.Love you all.
Regards

[DavidGee]

Rob, I have used back button focusing on my 50D for about 12 months now and would never go back to using the shutter release button. As I said once you have got used to it it is so much easier. With the shape of the back of the 50D near the AF-ON button I find my thumb just sits there naturally.

David

[carregwen]

Rob, I have used back button focusing on my 50D for about 12 months now and would never go back to using the shutter release button. As I said once you have got used to it it is so much easier. With the shape of the back of the 50D near the AF-ON button I find my thumb just sits there naturally.

David

Yes, it does seem quite a natural feel, I must admit. I've been meaning to change this for some time, but never got around to it. I'll give it a go!

[DavidGee]

Hello all,
Absolutely wonderful.
It has worked. I set it to C.Fn IV -1.
But soon set it to C.Fn IV -2 and get use to use the back button for focus as proposed here.
Donald is correct in I also find my thumb reach for *button while looking through my view finder. But this is my beginning to use in such manner. Soon teach my thumb to reach the correct button or follow as Donold's suggestion

I started to worry if my Canon 40D was faulty!!
Thank you very much guys.Love you all.
Regards

Snowshine, it is C.Fn IV - 1, Option 2 (on a 50D) that you want...Metering start/ Meter + AF Start. Just use your thumb to AF take your thumb off and recompose then press the shutter release and you are away with Focus/Recompose.

David

[rpcrowe]

This is a great answer to a problem which I did not know that I had... Thanks for posting this link! I have tried the sequence and it seems to work. Now, if only my ancient brain can wfunction the way I want when I am out shooting real images. I will test it this weekend.

I have decided that I will only upgrade to the 7D from my present cameras when I have exhausted all the capabilities of these cameras. Posts like this remind me that I am a long way from total use of every parameter I have at my disposal with the present equipment...

[snowshine]

Snowshine, it is C.Fn IV - 1, Option 2 (on a 50D) that you want...Metering start/ Meter + AF Start. Just use your thumb to AF take your thumb off and recompose then press the shutter release and you are away with Focus/Recompose.

David

You are correct. I was hasty in replying.
C.Fn IV -1, and then chose Option 2 in my Canon 40D to keep the focused subject locked while recomposing the scene.

Thank you.
Regards

[Dansk]

This is something I discovered only a couple weeks ago on my Olympus. I'd wished for this option a dozen times independently, but apparently I didn't read the manual closely enough to realize that my camera already had it. It was a great big "Ah HA!" moment when I finally realized how to separate the shutter release from the AF, like a great big realm of possibilities opening up.

[Colin Southern]

You should be able to focus & recompose by default - providing that the camera is in 1-Shot AF mode. Are you sure that you haven't got the camera in SERVO AF focus mode?

[Dave Humphries]

You should be able to focus & recompose by default - providing that the camera is in 1-Shot AF mode. Are you sure that you haven't got the camera in SERVO AF focus mode?

I have to say this was my first thought too, but I didn't know the Canon 'lingo' to describe what I meant and using the wrong words would only make it worse.

Thanks Colin.

Cheers,

[snowshine]

You should be able to focus & recompose by default - providing that the camera is in 1-Shot AF mode. Are you sure that you haven't got the camera in SERVO AF focus mode?

Hi Colin
Yes my attempts were while camera was in AL SERVO. Do you feel if that is set to ONE FOCUS it would have worked?
I have three choices to choose from AL SERVO, AL FOCUS, ONE FOCUS .
Regards

PS: I just tried it: Yes once I set it to ONE FOCUS the focused image is maintained when re-composed the scene.
Thanks Colin

[Donald]

Snowshine

Glad you managed to get it working. Yes, the sole purpose of AI Servo is to keep in focus whatever you are pointing the camera at. It is specially designed to deal with moving subjects. That is why the focus adjusted every time you re-composed your shots. Try it set on AI Servo with a moving subject. Then you will see how good that is.

Once you feel comfortable with the controls and settings on your camera, you should consider setting it up so that you use 'back button' focus. I think it makes focusing and composing much simpler and gives more control options.

[tonga]

Hi snowshine,

It may be worth it to read this [1] article about the focus-lock/recompose technique. It helped me a lot a while ago when I thought my camera was broken for not focusing correctly.

[1] http://visual-vacations.com/Photogra...pose_sucks.htm

Hope it helps.

cheers,