Could someone explain the AF/AE lock function?

[oneronnalee]

As above.

Basically after revisiting some technical information about my camera I stumbled upon the AF/AE lock function. I'm using a Nikon D3000. Could somebody explain this feature and how to put it into action? How and when do you use this function? Or, if you have a good website/tutorial on it, could you link me to it? I've done some googling but haven't found anything that would sufficiently clear it up for me.

Much appreciated.

Ronna

[inkista]

Try this: When should I use "AE" Lock?

[JFSanders]

AF/AE is there to allow for recomposing without losing your exposure metering and or focus point. This is for situations that you would underexpose your subject against a bright background or if you want to keep your focus point but to recompose the scene. It can be modified int the CSM (custom settings menu) on the higher level cameras and may be slightly modifiable on the D-3000.

You set what it locks while shooting by:

MENU > WRENCH > Buttons > AE-L/AF-L.


Jim

[oneronnalee]

Thanks guys, I think that clears it up for me a little - and I think it's time to do some reading on metering. Just so I absolutely understand this:
"...or when you wish to expose for the background and then recompose and shoot a photo"
- could you give me a scenario of what would occur if the AE-L was not used in this situation?

Thanks again!

Ronna

[dalmorloson]

In a situation where you are trying for a silhouette for instance, you would lock on the bright background and recompose and shoot the subject. If you don't lock on the bright background the camera will expose for the subject and there would be no silhouette. The subject would be exposed properly with a blown out background or the sub. would be a little underexposed with a little overexposed back.

[oneronnalee]

Thanks, that's a great example - but there's one thing I'm getting lost in - my assumption here is that I'll be shooting in manual, so unless I'm missing something, how can a camera expose 'differently' if I'd set it one way?

Again, thanks for the patience and the replies

Edit: is this perhaps mainly applied in Aperture/Shutter priority modes?

[JFSanders]

Originally Posted by oneronnalee

Thanks guys, I think that clears it up for me a little - and I think it's time to do some reading on metering. Just so I absolutely understand this:
"...or when you wish to expose for the background and then recompose and shoot a photo"
- could you give me a scenario of what would occur if the AE-L was not used in this situation?

Thanks again!

Ronna

It would depend upon what exposure mode you were in when you were making the photograph. As dalmorloson stated would be one such scenario. This will happen with frustrating regularity if you are in matrix metering or in spot metering with widely differing exposure values between subject and background. If you have the chance to pick up Joe McNally's book: The hot shoe diaries he goes a very long way in explaining this phenomena and how deal with this.

Jim

[oneronnalee]

Gotcha, thanks you guys

[Has]

Originally Posted by oneronnalee

Thanks, that's a great example - but there's one thing I'm getting lost in - my assumption here is that I'll be shooting in manual, so unless I'm missing something, how can a camera expose 'differently' if I'd set it one way?

Again, thanks for the patience and the replies

Edit: is this perhaps mainly applied in Aperture/Shutter priority modes?

Indeed.
If you're shooting in manual, Exposure Lock is irrelevant.

-Mark