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04-17-2011, 04:26 PM   #1
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The EV button confusion..

How many of us here use the EV button and move the wheel to get the appropriate reading???? I was never serious about it, until i discovered that as you increase it( in Av mode)the shutter value decreases...which i presume is letting the camera let in more light by keeping the shutter open longer...??? Exactly when do u mess with this feature..???? Its also linked to the flash when you activate it....I really can not pinpoint the difference when i bump it or bring it down....pls help...

04-17-2011, 04:51 PM   #2
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You use it when most of the subject matter is significantly darker or lighter than a medium tone, which will fool the light meter.

It you are metering off a black locomotive, the camera wants to make it gray. When metering a white cat in the snow, the camera will try to maker it gray.

So, for a really dark subject you need to underexpose to make it dark, and for a really light subject you need to overexpose it to make it bright.
04-17-2011, 04:52 PM   #3
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Well, if you're in Av and you adjust the EV, you are telling the camera that you want to use the same aperture setting but open the shutter longer to let in x number more stops of light. The Flash has it's own exposure compensation that can be selected when you select the type of flash you want to use.

When to use it? I spend most of my time in M mode and don't use EV Compensation. What you are doing is basically the same thing as going to M mode, pressing the green button to center your exposure meter, and then making an adjustment. The difference is, with EV comp in Av, the camera is taking care of that adjustment for you. In Av you also don't have to press the green button, the mode takes care of that step as well.

See This.. The Semi Auto modes (Av and Tv) are doing the same thing when you activate EV Compensation.

04-17-2011, 04:54 PM   #4

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Hi sagiboy,

Ev compensation is used to override the Program Line that the camera's metering system is using to either give more or less exposure than the meter deems as correct. With Flash it only works with P-TTL metered flash. If you find that your P-TTL flash is either over or underexposing, you can control it by either using Ev comp (faster) or by using Flash Comp in the flash menu (or both).

In Av, the shutter speed will necessarily be increased since you've specified the aperture, and if ISO is fixed, there is no other way to alter the exposure.

I use it in situations where the meter is easily fooled -- since I shoot birds, I'll give you a bird example. . .

Let's say a bird with a white breast is sitting in a shaded area. If the rest of the frame is also in shade, then the camera's meter will probably be correct. If the bird now moves so it's partially in bright direct sun, the white breast will most likely blow out, and if I want any highlight detail, I've got to tell the camera to underexpose the shot. Without changing anything else, I can dial in - EV comp in the amount that my experience tells me is a good bet. If the bird next flies up and lands on a naked branch and is silhouetted against the sky, it'll be significantly underexposed if I let the camera meter it, so I need to overexpose it to get any detail or color, so I use + Ev comp. I have all the cameras that have programmable e-dials to have the rear dial control the Av and the front dial to control Ev comp just for these kinds of situations.


04-17-2011, 05:23 PM   #5
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You guys are great..!!!! Thanks a ton....

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