AE lock use?

mw0dbb

mw0dbb

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John
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Can someone explain when I should use ae lock? Do I lock onto a dark subject and refocus on the light? Or the other way around. I have always wondered how to make a happy medium with image brightness?

John
 
mw0dbb said:
Can someone explain when I should use ae lock? Do I lock onto a dark subject and refocus on the light? Or the other way around. I have always wondered how to make a happy medium with image brightness?

John
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You lock it where you get a 'correct' exposure.
 
Very useful when spot metering. You can meter the area you want then lock the exposure and recompose.
 
mw0dbb said:
Can someone explain when I should use ae lock? Do I lock onto a dark subject and refocus on the light? Or the other way around. I have always wondered how to make a happy medium with image brightness?

John
Click to expand...

This is actually a much wider question about exposure, exposure setting and particularly exposure metering.

But say you were shooting a landscape with a bright sky. Because you know how the meter works, you also know that it will take all that bright sky into account, it will think the scene is brighter than it actually is in the foreground, and if left unchecked then the foreground will be under-exposed.

There are various ways of tackling that, but one very easy method is to simply point the camera down a bit to cut out the sky. The camera will then indicate more exposure, which is what you want. So press the AE Lock to hold those settings, reframe and shoot.
 
HoppyUK said:
But say you were shooting a landscape with a bright sky. Because you know how the meter works, you also know that it will take all that bright sky into account, it will think the scene is brighter than it actually is in the foreground, and if left unchecked then the foreground will be under-exposed. There are various ways of tackling that, but one very easy method is to simply point the camera down a bit to cut out the sky. The camera will then indicate more exposure, which is what you want. So press the AE Lock to hold those settings, reframe and shoot.
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But without evening up the exposure somehow would that not result in the sky being massively over exposed? I am not saying the way I do it is the right way to use it but I tend to use ae lock when I want one critical thing in a scene exposed correctly, such as a face lit by natural light in an unevenly lit room. If I allow the camera to average the exposure in that situation the highlights on the face may end up blown, whereas if I use ae lock, the most important part is properly exposed.
 
As I understand it, its for if you want a different exposure to where you are focusing. So if you have someone stod in front a window and you want to have them in focus but without blowing the light out behind them.
 
Nguss said:
But without evening up the exposure somehow would that not result in the sky being massively over exposed? I am not saying the way I do it is the right way to use it but I tend to use ae lock when I want one critical thing in a scene exposed correctly, such as a face lit by natural light in an unevenly lit room. If I allow the camera to average the exposure in that situation the highlights on the face may end up blown, whereas if I use ae lock, the most important part is properly exposed.
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Yes, the sky might blow, but with extremes of dynamic range like that you can't have both. The way around it is either a graduated filter to darken the sky, or HDR technique.

Raptor Mike said:
As I understand it, its for if you want a different exposure to where you are focusing. So if you have someone stod in front a window and you want to have them in focus but without blowing the light out behind them.
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Another good example of using AEL, though the wording isn't right.

Subject against a bright window would appear as a silhouette when metered normally, so move in close or zoom in, take a reading and apply AEL, then recompose. But the bright window will then be over-exposed and quite likely blown. The fix for that would be fill-in flash to brighten the subject so it's the same as the window.
 
Always seems to be a compromise. What is the easier to recover? Over or under expose? I mean in terms of using software, is the detail lost in these conditions?
 
Bracket exposures and blend/merge for a realistic exposure. Youtube is your friend.
 
mw0dbb said:
Always seems to be a compromise. What is the easier to recover? Over or under expose? I mean in terms of using software, is the detail lost in these conditions?
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If you have to, underexpose within reason. I find digital cameras are easier to recover shadows, but once highlights are gone they are gone. If you practice you will figure out what you can recover without introducing too much noise / other unpleasantness.
 
Nguss said:
If you have to, underexpose within reason. I find digital cameras are easier to recover shadows, but once highlights are gone they are gone. If you practice you will figure out what you can recover without introducing too much noise / other unpleasantness.
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If this is true - then why are there so many people that ETTR?
 
Because ETTR is about exposing right up to that point. Never beyond.

Recovered shadows are possible but soon get ugly, recovered highlights aren't really an option.
 
If I was to use filters then how dark should I go?
 
Phil V said:
Because ETTR is about exposing right up to that point. Never beyond.

Recovered shadows are possible but soon get ugly, recovered highlights aren't really an option.
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My thought is that I would try to get the correct exposure or may even go slightly to the right if I can avoid going too far. I never intend to under expose.
 
Dave Semmens said:
My thought is that I would try to get the correct exposure or may even go slightly to the right if I can avoid going too far. I never intend to under expose.
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If we use the oft misunderstood phrase 'there's no such thing as correct exposure'. Then exposing to the right gives us the best use of our sensor, ie. we record the maximum amount of information.

I'm not really an exponent, like you, I tend to veer towards slight overexposure. But the more photons we capture, the more information we have when we process our Raw files. Imagine the photo sites as buckets that catch photons, a black pixel captured no photons, a white one is full to the brim.
 
Dave Semmens said:
If this is true - then why are there so many people that ETTR?
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I think that the question was what was easier to recover, under or overexposure, and I may not have explained myself as well as I could have but personally think that underexposure is easier to recover. Once something is overexposed (in the sense of a pure white pixel) that information is lost. I find that where highlights are important if I have to choose between one or the other I would err on the side of underexposure if it means I can retain the highlights as I find it easier to recover or live with blocked shadows whereas over recovered highlights tend to look awful, but then having said that I can live with overexposed highlights in back and white more than in colour so it all depends on what you are looking for in the finished image.
 
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I always find my landscapes look flat and dull! I want shiny and clear look.
 
mw0dbb said:
I always find my landscapes look flat and dull! I want shiny and clear look.
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That's because you're shooting in flat and dull light.

If you want shiny and clear (contrasts), you need to go out in contrasts light.
 
The button is redundant if you are in manual mode. Many would refunction the button for "AF on".

But yes useful button if you are in aperture or exposure priority mode.
 
I don't get the purpose of the "AF on" button? Isn't it the same as pressing the shutter button half way?
 
Wow! What a handy feature.... Time for some practice!
 
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