Because you want to have the exposure set with one framing and focus set in another framing. It is extremely useful if you have contrasting scenes.VictorBucuresti, Romaniahttp://s106.photobucket.com/albums/m268/victor_petcu/..
Exposure lock is useful when you want to set the exposure using a specific target - perhaps not one even in the final shot..
The sequence goes:- Point it at the object you want to use to set the exposure- Lock the exposure.
- Recompose the shot and fire. Because the exposure was locked, the camera won't change it even though you moved it to a new subject..
A good example of where you'd do this is if you're using a "grey card". You'd point the camera at the card, lock the exposure, then reframe your actual shot. If you were doing this repeatedly, it's easier to set the camera to manual once you've determined the aperture/shutter speed/ISO you want to use than to keep locking the exposure over and over.http://flyheere.com/photogallery/album.ashx..
You use it if you want to fix the exposure in advance of composing the image..
An example of this might be where you want to expose for a small part of the scene only. By pointing the camera at that part of the scene to take the expsoure, perhaps walking closer to it, you can get the exposure right before worrying about the focus point and composition..
Of course, you can do the same by using manual exposure.Chris R..
Thank s, does it work when shooting people inside in front of window ? eg. focus and lock on grey card, then take shot in front of window..
You probably will blow the highlights coming in the window if you meter on the people. Conversely, the people will be silhouettes if you meter on the light coming in the window. The easiest fix is to move the people..
You probably will blow the highlights coming in the window if youmeter on the people. Conversely, the people will be silhouettes ifyou meter on the light coming in the window. The easiest fix is tomove the people..
Alternatively, add a dab of flash ("fill" flash) from the camera......
..... making sure that the potential flash reflection from the GLASS of the window is masked by positioning your subject(s) in between the camera and the reflection point.Regards,Baz..
You would use it to keep the same exposure when stiching a strig of panoramic shots together to fool the eye to see only one long photo. So you could do a complete circle (360 degrees) and the shot would have even flow due to the exposure being lock. Check out this site the photo are really cool. http://www.arnaudfrichphoto.com/.../english-version/photo-de-paris-pl5-en.htmTim..
Normally exposure is metered from the scene. However in some cases you want to use a different metering ( or force another metering ), AE-L lets you select the exposure then select focus and framing normally. In principle you can use it anywhere you want - you are the photographer, how you shoot is your choice..
I think learning to manually exposure a scene is a better idea ( albeit a hard thing to learn well )..
Regarding photographing through glass I am surprised to see flash being suggested. It sounds like asking for trouble ( reflections, flares, hard to predict ? ). Depending on the angles involved a circular polarizer can be helpful. You can sometimes cut down reflections from glass using a CP, although it's very dependent on the various angles involved, and can even be useless. You also loose a lot of light ( two stops is not unusual ). Again a useful skill to learn to use these..
Panoramas. AE-L is a possibility, but leaves the danger of over-exposure of one or more shot ( which it good to avoid ) and a manual exposure even a little under-exposed is the way I would go. ( Don't use a CP in panoramas, while I think of it - very bad skies happen ! ).
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