Exposure, then Focus (diff areas)??

I have a 40D and would like to know how to accomplish this...

How can I automatically set the exposure for one portion of the composition, but autofocus on another portion?

In other words, I want to expose for the early evening sky just above the horizon, but have the focus set to the main subject (say, a tree in the bottom right of the composition).

I would imagine the answer is not specific to the 40D, but similar to other EOS's as well (1D, 5D, etc.).

The answer is the same for all cameras.

Point it at the sky and set your exposure til the light meter reads correct (set ur aperture and shutter speed) and then bring the camera down and focus on the object by either using manual focus or by choosing the auto focus point.

If you are using modes other than "manual" you can use the exposure lock button, it is the "*". Expose on the part you want and then press the button and it will lock in that value so you can then recompose.

Strick wrote in post #4197970
If you are using modes other than "manual" you can use the exposure lock button, it is the "*". Expose on the part you want and then press the button and it will lock in that value so you can then recompose.

Alright, so that's what the "*" is for. Thanks.

CartoonBear wrote in post #4197954
The answer is the same for all cameras.

Point it at the sky and set your exposure til the light meter reads correct (set ur aperture and shutter speed) and then bring the camera down and focus on the object by either using manual focus or by choosing the auto focus point.

I just recently began shooting in manual mode, so I guess that makes sense, once the exposure is set manually, moving the camera and pressing the shutter halfway will focus on where ever the focus point is, not touching the exposure settings.

Thanks, everyone!

np glad to help

"*"


Among other things--I don't have the 40D yet but in other bodies there are 4 possible options that are set in the custom function menu.

I use Custom Function 4 set to "1". That moves the autofocus actuation from the shutter release button to the * button under the right thumb.

Now, whenever I wish to use autofocus I press the * button.

If I don't want to have the autofocus feature do it's thing, I just don't press the * button. That could be because I'm taking a series of shots that all should be focused the same or it could be because I choose to use manual focus. With the lenses I have ("L" zooms), I can use manual focus any time I care to, even if the switch on the lens is set to "autofocus on". By having the CF4=1 setting, pressing the shutter release button won't screw with the focusing I may have done manually.

SkipD wrote in post #4198437
I use Custom Function 4 set to "1". That moves the autofocus actuation from the shutter release button to the * button under the right thumb.

Now, whenever I wish to use autofocus I press the * button.

If I don't want to have the autofocus feature do it's thing, I just don't press the * button. That could be because I'm taking a series of shots that all should be focused the same or it could be because I choose to use manual focus. With the lenses I have ("L" zooms), I can use manual focus any time I care to, even if the switch on the lens is set to "autofocus on". By having the CF4=1 setting, pressing the shutter release button won't screw with the focusing I may have done manually.

Manual focus seems to becoming a lost skill; which is unfortunate for those that don't acquire it. And yes, the CFn 4/1 method is very useful.

When in the OP's situation, I'd use the spot meter to obtain the exposure level, and then set ISO, aperture, and shutter accordingly.

Others may have a different approach, and get the same mileage.