AE/AF lock

I need a little help with the AE/AF lock and the various settings on the D40. If I want to expose for the backround and use fill flash for foreground subjects, how do I refocus on the subjects when I move the frame away from the backround (which I need to lock the exposure on).

Also, what's the point of custom setting 13, AE Lock on/off when this seems to be covered in custom setting 12 and the various AE/AF combos?

One of the settings is AE lock only, and stays locked until you take the picture (rather than pressing the shutter half-way). So point at the area where you want to lock the exposure, press the AE lock button then compose and shoot.

I learned how to do this when trying to take a picture of my son looking at a sunset. The camera kept trying to expose to show my son and would blow out the sunset. Once I figured out that setting, it worked great.

rugger88 said:

I need a little help with the AE/AF lock and the various settings on
the D40. If I want to expose for the backround and use fill flash
for foreground subjects, how do I refocus on the subjects when I move
the frame away from the backround (which I need to lock the exposure
on).

Click to expand...

You can try using Slow Sync on the flash. This slows the shutter speed and balances the exposure of the foreground/background. You can set this manually, or use the "Night Portrait" scene mode. It's explained in your manual. This might require a tripod.

In PAS modes, if your AE/AF button is set to default, pressing it will lock both the focus and the exposure. If you set it to "AE Lock Only", it will lock the exposure until you release it, but won't affect focus.

Setting it to "AE Lock Hold" will lock the exposure when you press and release the AE/AF button. When you press and release it again, the exposure is unlocked. You have to be careful with this, as it keeps exposure locked through multiple pictures and you may forget you've left it locked.

rugger88 said:

Also, what's the point of custom setting 13, AE Lock on/off when this
seems to be covered in custom setting 12 and the various AE/AF combos?

Click to expand...

[13] controls whether pressing and holding the shutter-release button (not the AE/AF button) halfway will lock exposure. Normally it does not, but you can enable it.

What you probably want is [12] set to AE Lock Only, and [13] set to Off. Then you point to the background area you want to expose for, press and hold AE/AF, point to the subject you want to focus on and press the shutter-release halfway and hold, then compose the shot and press the shutter-release the rest of the way to take the picture.

The camera should be in spot or center metering to do this. Remember spot metering meters off the selected focus point, and center meters around a larger area at the center focus point.

is to set the camera in "Manual" mode; this will alow you to adjust the exposure to whatever you wish then recompose and focus without changing shutter and aperture settings. This works well for me but may take a little longer than using the lock after you become familar with it.

Hope this helps.
--
Kind regards,



letlightin

rugger88 said:

Also, what's the point of custom setting 13, AE Lock on/off when this
seems to be covered in custom setting 12 and the various AE/AF combos?

Click to expand...

Setting 12 changes the function the AE-L/AF-L button, setting 13 changes the function the half press of the shutter release button.

In setting 13 AE-L an be activated if the shutter release button is half pressed.

This way AE-L can be activated with the AE-L/AF-L button or the shutter release button.

This enables a lot of flexibility.

AF-L can be set to be only on the AE-L/AF-L button and AE-L on the shutter release button.

Or AE-L is just on the AE-L/AF-L button and AF-L just on the shutter release, or …

Thanks, I think this explains things much better than the user guide. I will disable option 13 and essentially use the AE lock button to hold exposure and the shutter to lock focus.

I've had my D40 for about a year now, and this thread has helped me understand the mysterious AE-L/AF-L button (which I didn't up until now!). Many thanks to all of you for clearing away the fog. I agree that you did a better job than the manual.