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01-18-2011, 10:11 AM   #16
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QuoteOriginally posted by Deiberson Quote
I have read the books and understand the principals of exposure that you guys are kindly reinforcing. What I don't understand though is this "Lack of EV Comp" in M.

I know that if my aperture is set to f/8 and I decide to open it to f/2.8 that I must also do something with either/both the ISO and shutter speed to compensate for the extra light that I just let in. I get that part. I was always under the impression that was my compensation. In other words, if my EV meter (maybe I'm calling this by the wrong name) in the bottom right of my camera was showing zero @ f/8 and I open up the lens 2 stops to f2/8 that my EV meter in the bottom right would now show "+whatever" because my scene is now over exposed because of too much light. I would then have to adjust (speed up) my shutter speed or iso (lower) to compensate for those extra stops in aperture to bring that meter back to "0".
Exposure value and Exposure value compensation are not quite the same thing, but they are related. EV refers to the total light level. On a bright, sunny day, the typical EV is around 15 or 16. You can achieve a technically correct exposure by many combinations of aperture, shutter speed and ISO setting, but all of those exposures are equivalent.

For example, you already know that, if the meter says 1/125 at f/8 is "correct", you can get an equivalent exposure by shooting at 1/60 at f/11 or 1/250 at f/5.6.

In one of the automatic modes, the meter in you camera will try for what IT considers a "correct" exposure. By choosing a different program line, or if you're in Av mode, selecting a different aperture, the camera will choose a corresponding shutter speed that achieves an equivalent exposure.

In some difficult lighting conditions, such as very bright sun accompanied by deep shadow or bright sun on a snowy day, the meter may pick a combination that is "correct", but looks lousy. This is where EV compensation comes into play. By setting +1 EV Comp., you are telling the camera to deliberately overexpose the image by one stop. Depending on the mode, it may decrease the shutter speed, open the aperture or increase the ISO sensitivity.

In manual mode, however, the camera is NOT in control. You are. The meter is simply telling you what IT thinks is the "proper" exposure. If you choose not to accept its recommendation, you can simply change the aperture or shutter speed. You read the meter, which is telling you, for example, to shoot at 1/125 at f/8, but you know that there are deep shadows, with detail that you don't want to lose, so you ignore the meter and shoot at 1/60 at f/8, or 1/125 at f/5.6. These exposures are NOT equivalent to the one the meter recommended.

Personally, I grew up using a Pentax Spotmatic, in which the meter had no control over the camera whatsoever. It was second nature to me, to center the meter needle (the camera's pick), and then, based on my experience, open up or close down a stop or two. So, it never even occured to me that my K10D was missing something until someone brought it up on one of the forums.

While I understand that in some situations, such as a manual lens that always over or underexposes by a fixed amount, EV comp in M mode might be useful, I don't think its necessary, and I don't think that its omission is a flaw in the camera. Others disagree. Different strokes, I guess.

BTW, if you haven't already heard of it, there is a great book by Bryan Peterson, called "Understanding Exposure" that does a far better job of explaining all this than I ever could.

01-18-2011, 12:12 PM   #17
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Petersons book always says something like "now that my camera is showing correct exposure", but never describes what that is. Are we to assume that propper exposure is when the +/- is at zero?
01-18-2011, 02:06 PM   #18
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QuoteOriginally posted by Deiberson Quote
Petersons book always says something like "now that my camera is showing correct exposure", but never describes what that is. Are we to assume that propper exposure is when the +/- is at zero?
Yes, that. He uses some phrases that take a bit of figuring out, such as "I turn the aperture ring until f11 shows the correct exposure", meaning "I turn the aperture ring until the correct exposure is indicated" (it just happens to be f11 for this one).
01-18-2011, 10:38 PM   #19
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QuoteOriginally posted by Deiberson Quote
EV compensation only deals with the amount of compensation that the CAMERA actually made, not the photographer. For the pictures I took in M, the camera made no adjustments. The adjustments I made where physical decisions on my part so there was no compensation that the camera needed to take. I "manually" overrided them. Is this correct?
Yep

QuoteOriginally posted by Deiberson Quote
When I switched to AV the camera wanted to keep my same settings at f/16 but the best it could do was .3" which in turn made my exposure +.7 as stated in my exif data? (this is the part I'm most confused about) Why did it not meter to "0" and make my exposure faster?
Confused as well

QuoteOriginally posted by Deiberson Quote
The last 2 shots in AV I manually controlled the +/- to get 0 and +2 and it showed in the exif. So why did it not show in M?
As EV compensation does not work in M mode, the camera will set it to 0 in the exif.

01-18-2011, 10:40 PM   #20
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QuoteOriginally posted by Deiberson Quote
Are we to assume that propper exposure is when the +/- is at zero?
From a camera perspective, yes. From an image perspective, not necessarily
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