20D AE Lock - DPChallenge Forums

Canon EF 17-40mm f/4.0L USM

04/11/2005 12:16:46 AM · #1

Does the AE Lock on the 20D work differently in Manual mode than it does on the 300D?

I have never been able to get the AE Lock to work in manual mode on the 20D, which was a feature of the Rebel that I thought was very useful esp. with partial metering.

The 20D manual (pg 148) seems to say that AE lock is user selectable in P,TV,AV, and A-Dep... but not in M.

The Rebel manual (pg 122) says AE lock is selectable in P,TV,AV,M, and A-Dep.

The Rebel-XT, and 10D documentation appear to be the same as the 20D.

(If this question has been previously asked in a different thread please redirect me to the appropriate post.)

KiwiChris

Canon EOS-5D Mark II

04/11/2005 01:10:21 AM · #2

Hi-ho,

AE lock in Manual??? AE = Automatic Exposure.

In manual mode the AE button will give you FEL (Flash exposure Lock) as per normal EOS flash functionality, but has no effect on normal exposure (Shutter/Apeture).

I've not used a 300D that much, so don't have any experience of what it actually does, but it would seem to be a bit of an oxymoron having AE lock do anything in manual mode...

edit: out of curiosity, what does pushing the AE button do in manual mode on the Rebel? I doubt it locks the exposure, as it's effectively 'locked' anyway in manual mode, and I don't think the rebel has FEL? (Unsure on that one...)

Cheers, Chris H.

Message edited by author 2005-04-11 01:11:17.

Prof_Fate

04/11/2005 01:39:04 AM · #3

The rebel has no FEC, but does have FEL.

KiwiChris

Canon EOS-5D Mark II

Canon EF 17-40mm f/4.0L USM

04/11/2005 01:44:21 AM · #4

Originally posted by Prof_Fate:

The rebel has no FEC, but does have FEL.

OK..

As a man with a 300D in his hands (so to speak), what does pushing the AE button do when in manual mode?

Cheers, Me.

04/11/2005 02:08:13 AM · #5

It would lock only the exposure reading when the AE button was depressed. It made no automatic adjustment to aperture or shutter speed, and adjustments to aperture and shutter speed remained independent.

04/11/2005 02:36:22 AM · #6

Memory is returning! =)

Pressing the AE Lock in manual mode was the Rebel's way to switch from center-weighted metering to partial metering. It was thru doing this that exposure reading locked.

04/11/2005 01:35:47 PM · #7

I spent over 45 minutes with a Canon tech this morning. The tech had a lot of difficulty understanding the point until he actually picked up a Rebel, set it to M mode and pressed the AE lock button.

What happens is quite different than with the XT, 10D, or the 20D and it's not easy to describe unless you have camera in hand. What happens with the Rebel when you press the AE lock in M mode is quite different than what happens with the Rebel when you press the AE lock in TV/AV/P mode. Perhaps the signifcant part is that the AE lock is the Rebel's way of switching to partial metering in the creative modes. That helps to explain why the AE lock function is available in the M mode, only on the Rebel. I don't know if this function remains the same if using a hacked firmware.

What I especially liked about it was that it locked the exposure reading while keeping the camera in M mode. There has been a lot of people who have upgraded from the Rebel. If I'm the only one missing this feature I must be taking the wrong approach.

riot

Canon EOS-1D Mark IV

Helios 40-1 85mm f/1.5

04/11/2005 07:13:31 PM · #8

I might be misunderstanding something massively, but... WHY would you want to lock the exposure READING?

04/12/2005 11:54:10 AM · #9

This allowed me to very rapidly zoom in and get and lock a reading, recompose and make any necessary adjustments to aperture and shutter speeds, observe the impact of those adjustments in the exposure meter; and NOT be concerned that the camera was no longer directed toward where you originally took the reading.

Not much benefit if you're using evalutive metering, but with partial metering I thought it to be nice.

edited to add;

Eugene, if it's of any help.. what I'm trying to explain is how Canon designed the Rebel. On the Rebel it is impossible to use partial metering in M mode without pressing the AE lock, thereby locking the metered reading. It was a feature of the Rebel that I liked.

Message edited by author 2005-04-12 12:53:50.

riot

Canon EOS-1D Mark IV

Helios 40-1 85mm f/1.5

04/12/2005 10:01:47 PM · #10

Ah, it hadn't occurred to me you'd want to see the results of your changes reflected in reference to the pre-metered scene... i guess i understand now, but i still cant imagine a situation where i'd use that. If i just want to set the overall exposure to a certain value relative to the scene, i'd just use shutter or aperture priority with exposure compensation adjusted to what i want the exposure to be, then just meter and shoot the scene that you'd meter first with your method... just seems more efficient, or is there something more to it that i'm still not getting?