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-   -   7D independent focus and exposure technique (

suethomo Oct 26, 2005 3:46 PM

Can someone help me with a user problem with my 7D - I am using the honeycomb-pattern metering mode. I focus using spot focus by pressing the center of the contoller on a close subject. I then keep holding the center button down and recompose my shot but the exposure is also locked. When I try this method using spot metering or center-weighted metering, the exposure changes and I can take the shot. I have also been trying to use this method to focus on a subject a third of the way in the frame. So I hold the center control buttom and the focus works fine but again it locks the exposure. This only seems to happen when in the honycomb-pattern mode. Can someone explain why this is so or have I got a setting wrong somewhere. I guess one could do it the other way round and use the exposure lock buttom to take the exposure and then focus on the near object and then take the shot but then if the exposure changes in the meantime it is a pain. Any suggestions?


JimC Oct 27, 2005 10:36 AM


Be patient. If someone knows an answer, they'll respond (I removed the duplicate posts on this issue). :-);)

Welcome to the forums. I recently got a 5D (versus 7D like you), and I haven't found a good way around it (not that I *really* must have this ability).

Most of the time, I just use a half press of the shutter button to lock both focus and metering anyway. Then, I recompose before pressing the shutter button the rest of the way down.

I'm used to Center Weighted Metering, and I try to judge how much (if any) Exposure Compensation I may want to use by "eyeballing" a scenein most cases (erring towards underexposure if in doubt to try and preserve highlights if other parts of the image are important). Or, for more extreme conditions, I may select a spot to meter on and/or decide how much Exposure Compensation is needed based on metering differences in different areas of the image. I'll admit that sometimes I dometer a given area and lock metering first though (for example, tilting the camera so a little more sky is in a viewfinder before locking metering).

But, in most conditions, using a half press to lock both focus and exposure before recomposing works fine for me. l'll admit that the Center Weighted metering in the 5D is going to take some getting used to, though. It doesn't seem to place quite as much emphasis on the center of the frame as I'd like (and it's not adjustable other than going to spot from what I can see).

For many photos, I'll probably just stick to Matrix from what I'm seeing from it's behavior in Center Weighted Metering mode. Any camera's metering behavior will take some "getting used to", and I'll reserve judgement until using this one for a longer time frame to find out works best more often.

Maybe I'm missing something, too.You can't override matrix metering once you lock both metering and focus using a half press of the shutter button (not that cameras are designed so that you can). That would work better in situations where you may want to focus on one subject, then press a button to meter *after* recomposing without releasing the shutter button, if I were designing a camera.

As for whether or not other techniques can prevent you from locking exposure when using Matrix metering (center button for focus lock), I haven't tested it much (but the meter still changes). LOL It may be just the camera's meteing display in the viewfinder changing (and it really is locked for the actual image). I haven't tested it to find out.

No camera is perfect. But, I'd add this to a "wish list" of future refinements in firmware (an option to press the AEL button to remeter after you lock AF with a half press of the shutter button and recompose, or use the center controller button for focus lock). I could be missing a setting somewhere for this purpose, too. I haven't played with all combinations yet (center controller button for focus lock, then AEL button after recomposing, then press of shutter button, etc.).

With my little Konica KD-510z, I can lock AF witha half press of the shutter buttonand a press of the up arrow, or lock AE with a half press of the shutter and press of the left arrow, and they work independently of each other. LOL

I don't think there is a perfect answer to your question. You'll need to lock metering, then lock focus and recompose if you want to meter on a different area first with Matrix metering (hoping that the scene didn't change in the interim) from what I'm seeing from my limited testing so far. But, I may be missing something, too.

Is this ability that critical (where your focus point is often metered that much differently after recomposing)?

A half press of the shutter buttonbefore recomposing locks both focus and exposure (which works well enough for me most of the time when combined with Exposure Compensation for scenes that may need it, without all of the extra button presses).

suethomo Oct 27, 2005 11:42 PM

Thanks for reply - I posted serveral times because I could not see print (black against black?) Cheers


photov Nov 9, 2005 2:12 PM

Hey all!

A great technique is to use the center-weighted metering, or the spot-metering. Set your settings for the "ae-l" button to "toggle" not "hold". Then point at something in your image view totally black, and set your ev to 0. That way, when you turn your camera to take the picture, it wont change your exposure, but will lock it based upon the black object you pointed at.

If you do this with a white object, overexpose by 1 stop. Eitherway, you will notice that your shutter speeds and apertures are the same.

hope this helps!

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