AE lock on Canon 7D

[Bill Yeung]

Hello all:
If I press the AE lock of my 7D to lock the exposure, how long the locking exposure will last?
Do it last until I press the shuttle button for a photo?
Do it have relation if I set the metering time longer and the locked exposure will lock the time I set?
As there is no explanation in the manual, (MAy be too simple and they never expect dump like me can ask this question!!)
I know definitely somebody here can help.

thanks, first.

Bill

[Jim B.]

Hi Bill,

Exposure will remain locked as long as you keep the shutter button half pressed.If you take your finger off the shutter button AE lock will stop after 5 or 6 seconds.

[Bill Yeung]

Jim:

But, (a) I point to a certain spot I need to lock exposure, then I press the AE lock right there.
It will be some second before (b) I turn my camera to compose a frame before I press the shutton buttom to set the auto-focus...

How long is the time between (a) and (b) is what I am concerning with.

Or I can ask in another way. How long the AE locked exposure will stop if no shuttle buttom is half press.

Excuse me for my English. YOu know that.

thanks

Bill

[Donald]

Bill

It also depends on how you have your camera set up. The best way of ensuring you understand this is to study the User Manual that you got with your camera. It should tell you for how long AE lock is active after you initiate it. As Jim indicated, the time between a) and b) is likely to be something like 5 or 6 seconds. On my Canon 40D, it is 4 seconds.

[Jim B.]

Bill,

You're English is fine.
I'm going by my camera,5DII.I forgot that the 7D is closer to the 1D series in setup.The manual is a good place to look for your answer.There's hardly any in depth information on the web about 7D settings.

[Bill Yeung]

Donand and Jim:
this is the problem.
Canon manual is small yet too simplified.
Even though I bought another Riley publisher book expalining the 7D.
Still, both places haven't answer the time between point (a) and (b).
If it is around 4-6 seconds, Then, I think the right procedure should be compose the frame first, then focus on the exposure, lock it , then back to the composed frame. By this way, 4-6 second should be more than enough.

LIke Donald said about the set up. It is also my first post asking whether the metering time setting means the locked exposure locking time.

actually, if I really bring the camera to do a field test, logging down the shots.....I should be able to find out the answer. But, Vancouver weather is rainy, cold.. and there is not much scene at home to have such a big exposure contrast.
it is only my lazyness that find some quick answers here.

Thanks, and will try it out.

thanks

Bill

[ktuli]

Bill,

I referred to my Magic Lantern Guide for the 7D, and it reports that the AE lock system stays on for about 4 seconds before it shuts off.

If you don't have one, I highly recommend them, I have one for both my Rebel XT and my 7D. They're like the manual but much more informative. And for $12, it is well worth it - http://www.amazon.com/Magic-Lantern-.../dp/1600596649.

Alternatively, keep in mind that AE Lock is only useful in P, Tv, and Av modes. If you feel that your composition will take a little longer, simply switch to Manual mode, meter your scene, set your exposure, and then the exposure is set until you change it. You can compose, take shots, recompose, take more shots, heck... you can even turn the camera off and back on again, and it will still have the exact same exposure settings set.

Hope this helps.

- Bill

[Donald]

Alternatively, keep in mind that AE Lock is only useful in P, Tv, and Av modes. If you feel that your composition will take a little longer, simply switch to Manual mode, meter your scene, set your exposure, and then the exposure is set until you change it. You can compose, take shots, recompose, take more shots, heck... you can even turn the camera off and back on again, and it will still have the exact same exposure settings set.

Bill
Exactly! That, I think, is one of the most important things to learn about in relation to exposure management. I work in Manual all the time. That is why I had to go back and read my manual when you asked your question about AE lock. I had forgotten how to use it.

[Wirefox]

Bill

Exposure is locked as long as you keep pressure on the * button. Once you have locked your exposure you can recompose then refocus using the shutter button. If you have your thumb on the * button depressing the shutter will only refocus not remeter so the AE lock time-out is disabled as long as you have your thumb on the * button so you can take as long as you want to have a beer, groom the dog...whatever There are times when this is impractical - tripod shots for instance - shooting manual is you best bet with a tripod

As said above if you take your finger off the * button you have 4 secs (for a 40D at least) or pressing the shutter halfway again will release the time out and cause the camera to remeter.

TIP: don't take you thumb off the * button when recomposing and refocussing then the exposure lock time out becomes irrelevant.

As Donald has said above (and I have finally listened) shooting manual frees you up of having to play the camera buttons like an accordion. There is a place for the semi-auto modes though you just need to decide for yourself when and where.