Focusing Problems with 50D

wegotitugetit

wegotitugetit

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alex
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right im currently using my camera in a studio i use the eye as a focus point to lock on to the move the camera to frame the shot

but when i take the shot (please note finger is still locked on the half way position so is locked ) it is blurry sometime's so i have checked the where i am focusing on and it has moved

so this is obviously moving the focusing point

im using one shot in the auto focus part of the camera

and also

it is is only one focus point not mulitple

im lost for idea's now ?

anyone help

i think the camera is overriding the settings some how im stuck on this
 
If you keep your finger down it will refocus when you move to reframe, maybe only slightly, but enough obviously

Try back button focusing, takes AF control away from the shutter button

How about using live view too, should be fine in a studio
 
Alex,

Try setting CFn IV 1 (Shutter Button/AF On button) to 3 (AE lock/metering + AF start)

This will allow you to focus with the * button on the rear, release the button, recompose and then the shutter button will just do the metering and take the shot.

Careful when recomposing if you're using a wide aperture of are very close as the slight angle you turn the body through will move the focal plane outside the DoF limit you want.

Bob
 
Your problem is due to shooting in single shot mode. When you half press the shutter button in this mode you obtain focus which is confirmed by the green light in the viewfinder (and the beep if you have it enabled) The problem is the focus is now locked, and even if you move the camera around that focus position still stays locked as long as you hold that half pressed position.

I appreciate you're not likely to start moving the camera around when shooting a portrait, but the problem is the longer you hold that half pressed postiion (composing or directing the model) the more likelihood there is of slight movement of yourself and/or the subject which throws your shot out of focus.. The answer is to obtain focus initially, then take you finger completely off the shutter button. Your next press of the shutter button needs to be a very smooth complete press, with a slight pause to confirm focus then press all the way.

A far easier solution is to shoot in servo AF mode when the camera will continually focus all the time you have the shutter button half pressed. I rarely shoot in single shot mode for the above reasons.
 
CT said:
Your problem is due to shooting in single shot mode. When you half press the shutter button in this mode you obtain focus which is confirmed by the green light in the viewfinder (and the beep if you have it enabled) The problem is the focus is now locked, and even if you move the camera around that focus position still stays locked as long as you hold that half pressed position.

I appreciate you're not likely to start moving the camera around when shooting a portrait, but the problem is the longer you hold that half pressed postiion (composing or directing the model) the more likelihood there is of slight movement of yourself and/or the subject which throws your shot out of focus.. The answer is to obtain focus initially, then take you finger completely off the shutter button. Your next press of the shutter button needs to be a very smooth complete press, with a slight pause to confirm focus then press all the way.

A far easier solution is to shoot in servo AF mode when the camera will continually focus all the time you have the shutter button half pressed. I rarely shoot in single shot mode for the above reasons.
Click to expand...

Not sure I agree with you CT, if you want to compose the shot it such a way that one of the focus points doesn't fall on the area you want to focus on (eye!?) then servo mode isn't going to help.

I think the OP is going about it the right way i.e use AF one shot, select the focus point closest to the area you want to focus on, half press the shutter to focus (ok, AF-ON button if thats your pref), recompose, and fully press the shutter.

If you're getting out of focus shots like that then one of 3 things is happening;

1) You are moving the camera nearer/farther to/from the subject while you're recomposing.
2) Your subject is moving nearer/farther while you're recomposing.
3) You are changing the focal length while you are recomposing.

This will be more apparent the lower the f number you're using.
 
jontucker said:
Not sure I agree with you CT, if you want to compose the shot it such a way that one of the focus points doesn't fall on the area you want to focus on (eye!?) then servo mode isn't going to help.
Click to expand...

Well that's true Jon although the OP doesn't talk about recomposing after acquiring focus. Even so (even allowing for recomposing) I'm sure the problem is hanging onto to that half pressed position too long after acquiring initial focus.
 
wegotitugetit said:
i use the eye as a focus point to lock on to the move the camera to frame the shot
Click to expand...

CT said:
Well that's true Jon although the OP doesn't talk about recomposing after acquiring focus. Even so (even allowing for recomposing) I'm sure the problem is hanging onto to that half pressed position too long after acquiring initial focus.
Click to expand...

Broken English :naughty: but I took that bit to mean recomposing! I think we're on the same page though!
 
LOL. Well assuming he's obtaining focus accurately in the first instance before recomposing, then his problems can only be hanging onto that half pressed position too long. I don't think we're actually in disagreement about that.

If he were shooting with a lens such as the 85mm 1.2L, then the lens is so extreme it wont allow you to take liberties like recomposing - not wide open anyway. We didn't establish what lens he's shooting with which might be a factor.
 
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