Metering Modes

So I'm pretty sure I have a clear understanding of WHAT the various metering modes (spot, center-weighted, evaluative) ARE, but I'm NOT sure of when to use a certain mode.

I pretty much leave it on evaluative, and I don't even know if that's the "general fallback" mode to even use.

Can anyone help clear up the situation(s) in which you would use each metering mode?

Most of the time, it is evaluative metering

Partial metering can be used in certain circumstances, i.e. where there is no spot metering available, like my camera, the Canon 400d, to mimic spot metering

I don't care for Evaluative even though it is all high-techie and sounds impressive. It doesn't work well with only a single focus point manually selected, it needs the feedback from the Auto Point Selection system. I almost always use only the center focus point. Since Evaluative weights the active focus point you would expect that combined with the center point the result would be the same as Center Weighted, but it doesn't always happen. Maybe the reference to the data base makes Evaluative unpredictable.

I use CW for action shooting and Spot when shooting something that allows me time to look for the brightest highlight in which I want to preserve detail, to meter off it and to add two or two and a half stops of exposure.

Evaluative is the mode where you want to try to expose everything. Struggles with extreme highlights/shadows.

Centre weighted - where you want the thing in the middle to be exposed correctly but retain the detail in the background.

Partial and spot - where you know you want the item under your selected focus point to be exposed correctly even at the expense of everything else.

Example of a person in front of a very well lit window:
Eval would reduce the exposure to prevent the highlights blowing out, therefore under exposing the person.
Centre weighted will cope better but will still try to reduce the exposure to prevent the hightlights blowing out. Detail of the face should be better.
Partial/Spot will expose the person properly ignoring the background. Blown highlights will be possible but the subject is exposed properly.

This is my "general fallback" mode, & except in very special situations, it works well for me: Need an exposure crutch?

Why?
Post #47

neilwood32 wrote in post #9702400
Evaluative is the mode where you want to try to expose everything. Struggles with extreme highlights/shadows.

Centre weighted - where you want the thing in the middle to be exposed correctly but retain the detail in the background.

Partial and spot - where you know you want the item under your selected focus point to be exposed correctly even at the expense of everything else.

Example of a person in front of a very well lit window:
Eval would reduce the exposure to prevent the highlights blowing out, therefore under exposing the person.
Centre weighted will cope better but will still try to reduce the exposure to prevent the hightlights blowing out. Detail of the face should be better.
Partial/Spot will expose the person properly ignoring the background. Blown highlights will be possible but the subject is exposed properly.

Whoa, I needed that info as well

I am on evaluative almost all the time.
You learn how the camera meters and also learn how to compensate.
I wouldn't get too hung up on metering modes. They are just different ways to get to the same place.

You use spot metering to meter off a small portion of the frame. So in the aforementioned case, you meter off of the person's face. It will be better exposed at the expense of blowing out the window. You meter off the window, and the person's face will be underexposed. There's always a compromise in extreme situations unless you use fill flash or bracket your shot and merge/HDR in post.

Whether you use Partial, Spot, or Evaluative, it really doesn't make a difference in terms of dynamic range.

Unfortunately a lot of the time people dont want to learn how to compensate for the metering (with EC).

Yes dynamic range doesnt change but the relative placement of that range does.

I'm an old-school shooter so use spot when I'm in manual mode (setting both the shutter and aperture manually). I've been doing this for decades so am pretty good at finding either a substitute for an 18% gray card (grass in sunlight, parts of the blue sky, etc.,) or metering the portion I want properly exposed. When shooting casually I use evaluative and TV (mostly).
Question for tzalman: You said "Evaluative weights the active focus point you would expect that combined with the center point the result would be the same as Center Weighted, but it doesn't always happen." Are you sure about that? All my 5D manual says is "after detecting the main subject's position" and it is my understanding that the algorithms used by these programs are more sophisticated than just using the selected focus point. I've read that they "evaluate" the entire image regardless of focus point to determine the main subject. Anyone else?

KCMO Al wrote in post #9708749
Question for tzalman: You said "Evaluative weights the active focus point you would expect that combined with the center point the result would be the same as Center Weighted, but it doesn't always happen." Are you sure about that? All my 5D manual says is "after detecting the main subject's position" and it is my understanding that the algorithms used by these programs are more sophisticated than just using the selected focus point. I've read that they "evaluate" the entire image regardless of focus point to determine the main subject. Anyone else?

Elie is probably asleep right now, but I'm "anyone else".

Evaluative does evaluate the entire image, and the meter biases rather strongly to the chosen focus point.

I did some tests with my 30D - probably valid for your 5D also, since they're the same generation. Try it yourself and tell us what you find.

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In the photos uploaded by number 6, could the algorithm not be able to detect a main subject? I'm guessing the algorithms were built around people being the subject. I've read that they built in a database of "typical" photos for the evaluative meters to use to determine the subject. I'll definitely try it out but I have not had any metering issues when I use it (and I only use the center focus point normally).

Well, I'd be hard pressed to identify a "main subject" in my test shots.

Exactly my point. I'll do some further research and see if I can find out more about the algorithms used by Canon.

nicksan wrote in post #9708476
I wouldn't get too hung up on metering modes. They are just different ways to get to the same place...it really doesn't make a difference in terms of dynamic range.

This.

For some reason a lot of people struggle with the concept of metering...and I appreciate that it's not totally intuitive, but the OP's question is a bit like asking;

"I understand inches and centimeters...but when do I use a 30cm ruler and when should I use a 30 foot measuring tape?".

The answer, of course, is; "it depends".

Or rather; "it depends on what you're trying to measure"...

Like most things, it helps to experiment and work out what suits you best.

I shoot almost exclusively in spot, but that's just me.

Evaluative biases exposure to the AF zone used for focus, but it still factors in the adjacent metering zones. As a result, Evaluative can readily be fooled about 'proper exposure' for a primary subject used to focus on. Here is an 18% gray card, which the AF point was used to focus, and which the meter used as highest priority to bias.