Question on Exposure compensation - technical`

[Ochman]

Hello all,
I understand how to use exposure compensation to either under- or over- expose a shot. What I'd like to know is how the camera does it. Does the camera increase/decrease the shutter speed? decrease/increase aperture? Does it depend on what exposure mode the camera's on?
Thanks in advance!

[Gonzo13]

Ochman I just played with the exposure comp on my 400D and here is what I saw. In Av mode it change the shutter speed, in Tv mode it changed the aperture, and in P I saw both change (it might have been because of me moving the camera, I was doing it all hand held).

~Gonzo13

[wulf]

It depends on what mode you are in. Personally, I shoot in manual mode most of the time and also have the camera set to leave the ISO alone, so exposure is all down to my choices.

Wulf

[kencaleno]

Bracketing in manual mode needs to be done manually-dependent on whether, speed or depth of field is most important at the time, you adjust aperture or shutter speed accordingly-Ken

[LoveDSLR]

Originally Posted by denja

I apologize. I have never used bracketing in manual mode, and was wrong in assuming that you could still use auto bracketing while in manual. I just double checked, and I must have been having one of those brain f***s again. Again, my apologies. My only defense is that user's manual describes auto bracketing as being possible in PASM modes. But it is NOT possible in manual.

Just for fun, I try it out with my Nikon & Canon DSLRs and both work in manual mode.

For example, Nikon:
Manual mode, f/2.8, 1/30 sec, ISO 200, auto bracket 3 frames at +/- 0.3 EV and the results are:

1/30 f/2.8 ISO 200 - 0 EV
1/40 f/2.8 ISO 200 - .3 EV
1/25 f/2.8 ISO 200 +.3 EV

[wulf]

Auto-bracketing in manual mode seems a bit of a misnomer; I don't have the option on my D40 anyway

It was one of the things I was concerned about when I got the camera but now, a couple of years in, I have to say that I haven't really felt the lack.

Wulf

[harrysixtie7]

As far as understanding how the camera works during exposure compensation, it is merely an adjustment to the light meter. The meter reads what comes through the lens and adjust ISO, aperture or shutter speed to compensate accordingly. That is why in manual mode, exposure comp is really quite useless. Sure it will change what your light meter reads or displays, but in the end you will have to make the adjustments yourself to make the exposure change happen.

[LoveDSLR]

Originally Posted by denja

I doubt, or at least I have never seen a camera, that you can set shutter speed in .3 and/or .7 stop increments.

My Nikon has this option:

Auto bracketing (Mode M)

Flash/speed
Flash/speed/aperture
Flash/aperture
Flash only

Another test with Flash/aperture option:

Manual mode, f/5.6, 1/30 sec, ISO 200, auto bracket 3 frames at +/- 0.3 EV and the results are:

1/30 f/5.6 ISO 200 - 0 EV
1/30 f/6.3 ISO 200 - .3 EV
1/30 f/5 ISO 200 +.3 EV

[LoveDSLR]

Sorry, I posted the wrong test results. Your comment was covered by my previous test.

With Flash/speed option, camera changes the shutter speeds (0,+/- EV).
With Flash/speed/aperture, camera will attempt to change the shutter speed first (0,+/- EV), otherwise apertures.
With Flash/aperture, camera change the aperture (0,+/- EV).