Metering Modes - How, When and Why to use them
Wednesday, December 17th, 2008
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If you own a DSLR, or even some point and shoots, you have one powerful feature at your fingertips, light metering modes. What are light metering modes? Let me explain.
Every time you camera takes a picture, it has to determine if there is enough light for the shot to be properly exposed, neither too light or too dark. If you are shooting in any of the semi-manual modes (P, Tv, Av, A-DEP) then your camera will make all the adjustments possible to expose the shots. Metering is automatic for auto modes and for manual mode (M) it tells your camera what the Exposure Value (EV) of the shot will be so that you can make manual adjustments.
But how does your camera determine that the shot is correctly exposed? Well, there are several methods and those methods are called your metering modes. For the following examples of the various metering modes, I will shoot in aperture priority mode. That means that my camera will adjust the shutter speed to obtain the correct exposure. I will shoot at f/4.5 for each shot.
Evaluative Metering
Center-Weighted
Partial Metering
Point Metering
Evaluative Metering
Evaluative metering is determined by a combination of subject brightness and positiong, foreground brightness and background brightness. The camera uses all that information to find the best exposure ballance for the shot. (the Nikon equivalent is 3D Color Matrix meterting)
This shot has the calculated subject, the bottles and candles, well exposed and just a touch of the background exposed.
a:f/4.5 s:1/4 ISO:100
 Center Weighted Average
CWA is essentially the camera saying that all light coming in is important, but that the light from the center of the camera is more important since that is probably where your subject is located.
Here we have more of the shot exposed because ambient lighting was factored into the overall exposure.
a:f/4.5 s:0.8" ISO:100
Partial Metering
Partial metering is the camera only choosing to correctly expose the center 9% of the frame. This mode does not factor in any exposure inormation from the edge of the shot.
The labels and candles are correctly exposed since they are in the center 9% of the frame. The rest is not correctly exposed at all.
a:f/4.5 s:1/10 ISO:100
 Point metering
Point metering is like partial metering exept that only the central 3.5% of the frame determines exposure.(point metering is called Spot Metering for Nikon)
The flame and top of the candle are correctly exposed because they comprise the center 3.5% of the shot. Even less of the shot is exposed than in partial metering.
a:f/4.5 s:1/25 ISO:100
So now you should have a basic understanding of what the different modes do. Light metering can help you ensure that various parts of the shot are either ignored when exposing an image (such a bright lights on the edge of the shot). Or metering can ensure the the subject in the center if your shot is exposed instead of too dark or blown out (such as a single candle burning).
That being said, having the wrong metering mode can cause problems too. Here is an example of point metering used on the wrong part of the shot.
As you can see, the light from the candles wasn't used in evaluating exposure and the shot, especially the labels near the candles , are over exposed. using Evaluative or CWA modes would have reduced the overexposure.
I hope that helps. Until next time. |
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There are 6 comments |
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hej,
i've been looking for short, comprehensive explanation of this stuff and i found it here. thanks a lot! |
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Posted by Marcin Pokorski @ 01/19/2009 4:07 PM |
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Just a note, this is very useful but I think the icon next to "partial metering" is accidentally a repeat of the "evaluative metering" logo. |
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Posted by Lori Ann @ 02/06/2009 8:51 AM |
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Great explanation (and photos) of showing metering modes. I'm really happy to find this and in easy to understand instructions. Thanks for sharing  |
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Posted by Kansas Allen @ 06/12/2009 8:28 PM |
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Wow! that was a very good illustration for a beginner like me, keep up your great efforts of sharing the knowledge |
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Posted by Sharoo @ 06/17/2009 3:03 PM |
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Great examples! Thanks.
Found @ http://digital-photography-school.com/introduction-to-metering-modes |
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Posted by Joe @ 09/15/2009 6:40 PM |
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FINALLY! I've read good information from several sources, but your examples and visuals made the differentce!! Now I think I can actually start messing around with the metering. Thank you! |
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Posted by Christina @ 10/22/2009 1:31 AM |
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