Exposure Compensation

Started Dec 31, 2012 | Questions thread
Topaz
Contributing MemberPosts: 588
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Re: Exposure Compensation
In reply to WilbaW, Jan 2, 2013

WilbaW wrote:

Topaz wrote:

The most important thing to note, I think, is that there was no discussion of metering modes.

What part of "I am in Manual mode" is ambiguous?

Oh boy, here we go. The answer is "the part where he does not mention if he is using evaluative, partial, spot, or center-weighted average metering". Please see page 119 of the 60D manual for a basic explanation of what these metering modes do. If you think "manual mode" is a metering mode, then you are more confused than the OP. We've determined the OP is using the in-viewinder meter in M mode to gauge his settings. The metering mode has a massive effect on what shows up on the viewfinder's meter.

If you doubt me, try this experiment: Put your black lens cap on a white piece of paper. Go to M mode, and make sure auto-ISO is disabled. Set your camera to spot metering mode (again, please see page 119 for info on how to do this). Fill the viewfinder with the sheet of paper, with the black lens cap under the spot meter, and adjust shutter or aperture so the meter reads 0. Now, change the metering mode to center-weighted average. Frame the same photo and look at your meter now. It probably reads +2.

I'm not confused at all.

What did you see when you tried the exercise I gave? What did you see?

I see that you were trying to prove you can take the same looking photo in both modes. That's a totally obvious point which we all know. However, please note you botched the specs for your "experiment". If you turn the dial counterclockwise in Tv mode you are applying negative EC, which effectively tightens the aperture (higher F number) and results in a darker picture. If you turn the dial counterclockwise in M mode you are decreasing the F number, meaning a wider aperture, and a brighter picture. So the answer is "yes, I can tell which was shot in which mode because the one in M mode is 2 stops brighter".

Even if you reverse the direction of the dial in M mode, your "experiment" only works because you rigged it by using Tv mode instead of Av mode (or P mode). In Tv mode the rear dial controls exposure compensation, which effectively means a change in aperture. In M mode, the rear dial is the aperture control. So they match. But had you used Av mode, it would be even more obvious which photo was shot in which mode, because exposure compensation for Av mode indirectly alters the shutter - not the aperture. So you're changing the shutter in Av mode, but the aperture in M mode by rotating the rear dial. The M and Av photos will have completely different DOF.

Of course they all affect exposure in the end, but the ergonomics are radically different, and the on-screen information means something different in semi-automatic modes and manual modes. Avoiding confusion like yours and the OPs is probably the reason none of the camera manufacturers use the terminology "exposure compensation" when they are simply talking about metering away from 0 in manual mode.

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