*AE lock question on my 40D

how exactly is this used. i have only been able to get it to work when i have my flash poped open. i shot mostly in Manual mode. as far as i understand, point to where i want to meter the exposure from (does this work in all 4 metering modes?) then halfpress untill i get the focus points locked, then press the * button and it should lock the settings so i can refocus. correct?

problem is i never get the * conformation when i press the * button.

any one have some insight?

I set Custom Function IV 1 to 3, and then I use the AF-On button for AF (feels natural to me), and then use the half shutter press for exposure lock. I meter, half press the shutter, recompose, and focus with the AF-on button. Works quite well.

burrito wrote in post #3992934
how exactly is this used. i have only been able to get it to work when i have my flash poped open. i shot mostly in Manual mode. as far as i understand, point to where i want to meter the exposure from (does this work in all 4 metering modes?) then halfpress untill i get the focus points locked, then press the * button and it should lock the settings so i can refocus. correct?

problem is i never get the * conformation when i press the * button.

any one have some insight?

In manual mode the exposure is already set - you have a fixed aperture and a fixed shutter, so the AE lock is note needed- your exposure is already locked.

That is how I understand it anyway. You'll need AE lock if you're using TV or AV, where the camera is selecting something for you - you expose, lock it, and recompose. When you set everything, what will the AE lock do? Fix the shutter and aperture that you have already fixed?

ah, didn't notice about the manual mode. Yes, obviously you've already set the aperture and SS, as noted above. There'd be nothing to lock.

but doesnt the metering have something to do with the exposure? like if i want to meter off a blue sky for a subject that is backlit by it?

well mabye its metering that im not quite sure about? any info on that? just got done reading understanding exposure and the the metering thing got me thinking but might have confused me more

If you want to meter for a blue sky, and you're in manual mode, just use the built-in light meter and switch to partial or spot metering. Pick the area you're metering for, and follow the needle in the bottom of your viewfinder. If you want it properly exposed, you may want to adjust shutter speed until the needle is around +2/3 or +1. The only time the camera will automatically meter for a given area is in the other modes, such as AV or TV. These are the only times one may need to "lock" exposure. The only reason to lock exposure is so that the camera doesn't continue to meter, given any potentially changing conditions. Since you're doing the "manual" metering in manual mode, there'd be no need for exposure lock.

ahhh gotcha. thanks

I nearly always use manual mode - I use the needle, and try and develop my own eye for exposure - if I want to overexpose because of a backlit scene, I dial in some over exposure until the needle is slightly to the right as Ronald said. Now, however, I have spot metering, so I might try that as a new technique.