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How good is Evaluative Metering?

Dillan Koropatnick , Jan 07, 2006; 08:31 p.m.

I'm a slide shooter with an Elan 7, and I've never been brave enough to rely upon evaluative metering. I use partial metering almost exclusively. I'm ok at it, but I still have to learn to trust myself more. I usually take a long time to meter my subject. I'd like to give the evaluative metering a try. Before I waste a roll of film, what can any of you say about it, both with and without flash (420ex). Thanks for your help!

Responses


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Mark U , Jan 07, 2006; 08:55 p.m.

It's much more of a pain switching between metering modes on an Elan 7 than on a Rebel (just push * to get partial metering to compare with evaluative that is otherwise standard in P, Av and Tv modes) or Elan II (lever). However, you will learn most by comparing scenes for yourself. Don't forget to explore the metering CF8 option.

So far as flash is concerned metering of the flash exposure is quite independent of the ambient exposure. Ambient metering for flash depends on the exposure mode and scene brightness relative to ISO. You would do well to read the flash bible here:

http://photonotes.org/articles/eos-flash/

Brad W , Jan 07, 2006; 09:22 p.m.

great for neg's

so-so for chromes

crappy for dslr's

The only way to learn exposure is trial and error. Bracketing will speed the learning process.

-b

Yaron Kidron , Jan 07, 2006; 10:29 p.m.

It's pretty good as long as your target image follows the 18% gray scheme.

David Y Lee , Jan 07, 2006; 11:18 p.m.

Really depends on what you shoot. But you should be able to get an idea by first metering yourself on partial, note the parameters, then switch to evaluative metering and see if the parameters are close to your own. If so, good; if not, you can expose two shots and see whether you or the evaluative is better. You have to experience for yourself when it's okay to use evaluative, and not to worry too much about film cost. For myself, if time allow, I like to meter myself. I don't shoot enough flash chrome to comment on that.

Paulo Bizarro , Jan 08, 2006; 12:15 a.m.

I only use slide film these days, and my camera is the EOS 1V. I find evaluative metering to be correct for around 95% of the time. I shoot landscapes and travel.

Sometimes, just for the sake of it, and to confirm, I compare readings from evaluative to spot, and they agree.

Vincent J M , Jan 08, 2006; 02:05 a.m.

Great on the film cameras.

I've owned and used an Elan2, Elan7, EOS3 and several others. Eval metering was excellent on all of them. 95% of my chromes were properly exposed.

Eval metering pretty much sucks on the DSLR's I've used, including my 300D. If I shoot JPEG, half the shots are incorrectly exposed, specially when using flash. I only shoot raw, and it needs exposure compensation almost 100% of the time. No big. Raw works.

Kirk Darling , Jan 08, 2006; 02:17 a.m.

>>The only way to learn exposure is trial and error. <<

I should say not. Exposure is a science and its srtistic application can be learned systematically. The best tool, IMO, is the Zone System, which was specifically invented as a learning tool for new photographers. To see how it applies to digital imaging and relates to histograms, check this site:

http://www.digitalsecrets.net/Sony/AdvancedKnow.html

Then Google a bit for the Zone System and learn how to expose intelligently.

Kirk Darling , Jan 08, 2006; 02:32 a.m.

How Evaluative Metering Works

When Evaluative Metering first came out with the Canon 650 (about the same time as the similar Nikon Matrix Metering), the photography magazines published detailed descriptions about how it worked. I still have my copy of the July 87 "Modern Photography" that had a stripdown test of the Canon 650.

Evaluative Metering is basically a "knowledge base" system. When you meter a scene, the system measures the light levels of each of the sectors then converts the readings into a mathmatic expression using a proprietary algorithm. It uses the activated focusing point to determine where the subject is as part of the calculation (which is why EM locks exposure with focusing).

It then searches its database of algorithms produced from tens of thousands of correctly exposed photographs (Nikon claimed 90,000 photographs for its matrix metering). The photographs include scenes with as many different lighting schemes as possible. When it finds a match, or the closest possible, it sets the exposure.

It can normally identify things like intentional backlighting and correctly underexpose the subject by a stop...but this presumes the photographer intended a "conventional" backlit scene. If the photographer wanted the subject fully silhouetted, the camera would not know that.

Also, like all meters, the EM system still presumes the subject should be medium gray. Therefore, if the subject is some other tonal level, the photographer should compensate for the subject difference--but not the lighting.

For example, if the subject was a backlighted white stallion, the camera would correctly identify the lighting situation, but would assume the subject was an 18 percent gray that should be underexposed a stop to preserve the backlighted effect.

If the horse would normally be Zone 7, and properly exposed for the backlighting at Zone 6, the camera would place it on Zone 4. Because the subject is two stops lighter than Zone 5, the photographer should dial in a +2 stop compensation for it.

Steve Dunn , Jan 08, 2006; 10:58 a.m.

I mostly shot negatives, with an Elan 7E and an Elan II before that. Occasionally, I'd shoot slide film. I found evaluative metering on the 7 a bit better than on the II, but both were pretty good for most situations. The only situation which typically caused problems was a backlit subject, and neither one handled those very well. But, knowing that, I could fix it by adding some exposure compensation.


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