Am I being stupid - 'locking focus'

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Rocket_Dog

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Jeff
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Hope this isnt a dumb question, but here goes...........

I have a Canon Powershot G9. Not had it long and still getting to grips with the manual settings etc.

But one thing that is driving me mad is locking in focus by half depressing the shutter. Im sure this worked when I first got it but now doesnt work at all.

I have it on automatic settings, AF frame set to centre (though I have tried it on AiAF). I then centre my subject, press the shutter half way down, then recompose the scene. Then take the shot. When I review the image on the camera it tells me where the focus point was - and its back in the centre. :bang:

I have made sure AF Mode is not on continous.
Have even reset all setting on camera back to when i first bought, to no avail.

Any guesses anyone ?
 
When you lock focus the point will not move across frame because you've reframed the shot. Locking focus simply means the distance you've focused at is locked rather that on a particular part of the scene.
 
hummmmm

So if im taking a pic, for example a solitary duck on water, and centre the duck, half press shutter, then reposition camera slightly to have duck on a 'third', then fully press shutter - that wont work. I will still end up with now empty water as my main focul point ?
 
Rocket_Dog said:
hummmmm

So if im taking a pic, for example a solitary duck on water, and centre the duck, half press shutter, then reposition camera slightly to have duck on a 'third', then fully press shutter - that wont work. I will still end up with now empty water as my main focul point ?
Click to expand...

no
the focus remains locked on what you originally focused on,,
the duck
 
soooooooo is it a distance thing then.
Im im slowly understanding this, then how about this example.

If my girlfriend is stood in front of a distant mountain and I centre her, then reposition so she is to the side of final shot with lots of mountain in view, it will still focus on her due to focal length I have locked it at.
 
If it helps, imagine when you half-press the shutter button a red sticker is placed on the subject where you focussed (in the centre of the screen). When you recompose the shot with focus lock on, the camera is still focussed at the range where the 'sticker' is, even though it may be in another part of the frame. You press the shutter all the way and take the shot.

When reviewing the image, the camera tells you where the focus was locked (where the sticker was) originally, not where the subject ended up in the frame.

:) Steve
 
Basically it means that rather than focussing on what the AF point that is highlighted seems to be pointing at, instead the focal point will be where you locked the focus in the first place, which may be either behind or in front of where the AF point suggests.

Try an experiment - find a scene with an item nice and close in front of you - a fencepost or pillarbox for example. Make sure it's still within an area that the camera can focus on, (ie, not so close that it's outside your range of focus) and directly in front of you. Focus on something well behind that item, lock the focus and shift your view so the item is in the centre of the frame, then take your shot. Repeat the shot focussing on the item itself, only this time shift your view once you have locked focus so that the item appears to one side or the other of the frame. In your first shot, the item will appear OOF, in the second, the background will be OOF. You will have back your faith in your camera! :D
 
All you kind gentlemen (and ladies if applicable) - you have restored my faith and prevented me from stamping on my new camera :clap: It was asking for it I tell ya.

I was such a twonk, I was doing test shots on things at the same focal length, ie side by side :bonk:

I obviously made some of my original test shots (when it worked) inadevertently doing it correctly but didnt know how or why.

Makes note to come on here and ask questions earlier, rather than pulling hair out.

Thanks one and all, muchly.
 
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