AE Lock


rocketatw

Senior Member
Jan 15, 2010
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Can anyone guide me on correct method of AE Lock, lost my manual and google online help, only managed to find the following steps, not sure correct. Let me know if it is wrong. I am using Canon 40D.

Steps:

1) Switch to AV/TV/P mode, use centre focus point.

2) Point Camera to a object(how to determine which object?) and half press to get the setting

3) press '*' button on the camera to lock the setting

4) Recompose the shoots and full press. (only have 10secs to recompose after step 3)



Is the above steps correct?

example:
from the below shots, which area should i determine for step 2?


arun-river.jpg
 

Last edited:
Why don't you download the manual from Canon?
 

Why don't you download the manual from Canon?

downloaded from Canon website, also check with a few website for AE Lock info, but seems different website giving different info.:dunno:
 

Can anyone guide me on correct method of AE Lock, lost my manual and google online help, only managed to find the following steps, not sure correct. Let me know if it is wrong. I am using Canon 40D.

Steps:

1) Switch to AV/TV/P mode, use centre focus point.

2) Point Camera to a object(how to determine which object?) and half press to get the setting

3) press '*' button on the camera to lock the setting

4) Recompose the shoots and full press. (only have 10secs to recompose after step 3)



Is the above steps correct?

example:
from the below shots, which area should i determine for step 2?

What you want to be properly exposed, would be the object you should select.

Which specific object is that, I would not know, because it is your picture and your composition. Only you know what is your point of interest and how you want the shot to turn out. :dunno:
 

2) Point Camera to a object(how to determine which object?) and half press to get the setting
If you use an Exposure Lock mode I don't know why the focus point becomes relevant here. Unless the metering for spot and center weighted is coupled to the focus point...
Apart from that, do read up about the different exposure metering modes and how they work. Next read-up: reading / judging a scene in terms of exposure. This will tell you where to point your camera at. Not necessarily the actual object...
 

is my steps correct in the first place.
 

is my steps correct in the first place.
If these steps are described in this way in the manual they might be correct. But we have pointed out numerous other things. Using the wrong metering mode will render all the steps useless. Not understanding a scene in terms of exposure will not give you the result you want to achieve.
 

If these steps are described in this way in the manual they might be correct. But we have pointed out numerous other things. Using the wrong metering mode will render all the steps useless. Not understanding a scene in terms of exposure will not give you the result you want to achieve.

base on the above picture, if i want to focus on the swan which opens its wing, what is the best AE Lock + metering mode you will suggest?

For me, i will use centre focus point, evaluating metering, focus in the swan and half press to get the setting, then Lock on the setting by pressing '*', recompose my shots( same as the above picture), then full press the shutter button.
 

base on the above picture, if i want to focus on the swan which opens its wing, what is the best AE Lock + metering mode you will suggest?

For me, i will use centre focus point, evaluating metering, focus in the swan and half press to get the setting, then Lock on the setting by pressing '*', recompose my shots( same as the above picture), then full press the shutter button.

If you want to focus on the swan, why are you concerned with AE lock?

Very crudely, AE lock is used when you meter for an object, you lock the exposure and take a photo (probably of something else) using that exposure locked it. It has nothing to do with autofocus!
 

If you want to focus on the swan, why are you concerned with AE lock?

Very crudely, AE lock is used when you meter for an object, you lock the exposure and take a photo (probably of something else) using that exposure locked it. It has nothing to do with autofocus!

what will be your way of settings if i ask you to take this picture?

showing the steps will greatly be appreciated.:)
 

what will be your way of settings if i ask you to take this picture?

showing the steps will greatly be appreciated.:)

since you are using canon 40D, it means you can only do spot metering at the center AF point.

So move the camera so the center AF point is on the duck that you want to expose correctly.

half press shutter, press and hold AE--L button, recompose the scene, press shutter down fully to shoot.
 

since you are using canon 40D, it means you can only do spot metering at the center AF point.

So move the camera so the center AF point is on the duck that you want to expose correctly.

half press shutter, press and hold AE--L button, recompose the scene, press shutter down fully to shoot.

As above- but only if you want the duck to be in focus and the rest of the scene more or less underexposed. Alternatively, you could meter against the duck (ie. spot meter mode, and point the center AF point to the duck), change to M mode and then dial in the required exposure.


But bear in mind that since the duck requires a faster shutter speed to be correctly exposed (I assume, since the duck is already blown out here), then the rest of the scene would be underexposed. You could take 2 seperate exposures and do a blend.
 

since you are using canon 40D, it means you can only do spot metering at the center AF point.

So move the camera so the center AF point is on the duck that you want to expose correctly.

half press shutter, press and hold AE--L button, recompose the scene, press shutter down fully to shoot.

thanks DD123,

i guess my steps is incomplete as i did not hold the '*' button after pressing. thanks for pointing out.

another question, if i point the centre AF on the swan, is it advisable for me to zoom closer to get the setting before i half press the shutter?
 

thanks DD123,

i guess my steps is incomplete as i did not hold the '*' button after pressing. thanks for pointing out.

another question, if i point the centre AF on the swan, is it advisable for me to zoom closer to get the setting before i half press the shutter?

no. Keep it at the focal length you want to shoot the picture at.
 

base on the above picture, if i want to focus on the swan which opens its wing, what is the best AE Lock + metering mode you will suggest?
You might focus (= direct your attention) to that swan, but 'focus' in terms of camera is where the picture will be sharp. I hope you see the difference. Focus and metering are 2 different topics. Sure, most cameras are able to handle this together but your example here shows a de-coupling. So you need to make sure you know which is which and how your camera handles it.

For me, i will use centre focus point, evaluating metering, focus in the swan and half press to get the setting, then Lock on the setting by pressing '*', recompose my shots( same as the above picture), then full press the shutter button.
Have you looked how evaluative metering works? Why do you want to use AE function if you use 'Evaluative'? Doesn't make any sense to me but maybe you can explain :dunno:
Again: your AE functions locks the exposure settings, based on the image and the metering mode you are using. If you want to get that swan properly exposed then use a metering mode that only takes the swan into consideration. Spot / Center weighted are hot candidates here. If you also want that swan and everything else in the same distance to be sharp (= in focus) then then just drop this AE button, use the above mentioned modes (one of them...), set the center AF to the swan, half-press shutter (and hold!), recompose, fire. Using a smaller aperture for landscape is recommended.
Understanding Metering (incl. modes)