Ae-lock and Re-Compose

Started 2 months ago | Questions thread
Bill Ferris
Bill Ferris Veteran Member • Posts: 7,284
Re: Ae-lock and Re-Compose

Jcbailey wrote:

hobbit mob wrote:

Jcbailey wrote:

I'm confused on how AE-lock works. I was adivsed and also tried this. Walk into a room point at what i want to capture, lock the exposure with AE-lock. re-compose and take the shot. in theory the shot should have the same exposure as when i locked it. I don't see this.

for example. i went into a dark room and found some light. i metered the light and my Shutter was at 1/200 to see if it was right i metered the dark spot and it was 1/60. so i Ae-locked the 1/200 from the light locked it re-composed and the shot came out dark. my camera focused again while i pressed the shutter all the way down and took whatever shot it wanted. I was in AV mode with a fixed iso.

What happend?

Unless I'm misunderstanding, that sounds like it did exactly what it was supposed to do. If the shot came out dark, I assume it used the 1/200 shutter speed? If so, it locked that in. If you metered against the light, it'll choose a faster shutter speed to try to get the light metered correctly, it will ignore the rest of the frame (if you have center weighted/spot metering on). The rest of the room should be dark and the light should be exposed correctly. If it re-metered in the dark area, it would choose a lower shutter speed (probably limited to 1/60 by default) to expose the shadows.

check your custom settings to see how you have your AE lock button and shutter set up. Check for press/hold, AF/AE lock settings, shutter settings (behavior when you press it, it can meter/take a photo/autfocus and some variations of those).

So let me get this correct if it metered at 1/200 it suppose to be dark because a higher shutter speed is dark. if it metered at 1/60 that means it has more light? is this correct? i was at 16000 iso. probably not enough light. i guess

Any shutter speed can be "bright" if there's  enough light in the scene.

Camera's are designed to make the world look middle gray in lightness. If you meter off a bright source (e,g. a light) and target a meter reading of 0, the settings will darken the light enough so it appears middle gray. That's going to be 1 to 2 stops  darker than it would normally look? By locking in those settings, the camera was forced to make photos capturing scenes darker than they look to the eye.

A shutter speed of 1/60 second is nearly 2-stops brighter in exposure than 1/200 and would have compensated for metering off the brightest part of the scene.

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