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06-01-2009, 10:18 AM   #1
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Metering Modes (on K20D)

Is the 16-segment metering mode to be trusted?

How should I go about using center-weighted and spot metering?

06-01-2009, 10:34 AM   #2
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For whatever reason, I just never used multi segment metering (which isn't to say that it isnt good) I'm sure it is quite reliable. Center weighted metering is if your subject fills a majority of your frame (ie. flower shots or close up portraits). The camera will give priority to exposing the center of your frame correctly and not worry too much about the edges. Spot metering is used when you have a small subject that you want to expose correctly for (for example you have a small white object on a mainly dark background or vice versa) you simply point the center af point at that object and it will only calculate the proper exposure based on that one spot.
I suppose if you're shooting wide landscapes or something without too much drastic variation between bright and dark areas, you should be ok with the multi segment metering.
06-01-2009, 12:17 PM   #3
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I would recommend the same thing for both your questions besides the good answers you will receive in the forum. Get out and shoot different lighting scenarios in all three modes and compare the results to see what works best for you in each circumstance. I have done that and found for my purposes, little difference between multi-segment and center-weighted even though i understand the theoretical difference. I just stick with center for all subject oriented shots and only use segment for occasional panoramics.
06-01-2009, 02:00 PM   #4
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Yes, Pentax's metering is 'trustworthy', with the caveat that Pentax favours metering to avoid highlight clipping, and so as long as you understand how each mode works, you should be able to get reasonably consistent exposures without having to adjust EC very much (that depends on the lighting situation and whether you are using the right mode for it).

06-01-2009, 02:55 PM   #5
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I'm sure Pentax's multi-segment can be trusted to produce exactly the results it was intended to produce. That doesn't include reading your mind, though. And I don't really pretend to be able to read it's "mind":either. So I prefer center-weighted, because I *know* how that works and therefore how to get it to produce exactly the results I want every time.
06-01-2009, 05:55 PM   #6
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I shot multi for a long long time with mostly good results. One recent gray-day shoot came out a bit dark, so I followed Marc's recommendation about center, and tried that for about a month. Didn't notice a whole lot of difference, though I did go back to multi just a week or so ago....

Check the histogram and review...

Last edited by SpecialK; 06-04-2009 at 08:46 PM.
06-01-2009, 06:44 PM   #7
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I use Spot pretty much all the time, except in very rare situations such as using a 10-20mm lens and I am going to litterally fill the "frame" with all sorts of objects/subjects.
Mind you, I use a 300mm lens about 80% of the time for bird/wildlife photography, so "Spot" is my choice. I have never used Centre Weighed Average.
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06-01-2009, 06:51 PM   #8
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Ok...I will fess up. I do use spot on two occasions so far; the moon in a dark sky and white egrets in the dark mud marshes. Always with the 55-300mm fully extended. Guess I need to check out jpzk's gallery shots and see what else you can do with spot.

06-01-2009, 06:54 PM   #9
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Check out Pentax Photo Gallery.
That will give you a better look at the Spot use.
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06-01-2009, 07:40 PM   #10
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you read my mind after i typed it!
06-02-2009, 01:00 PM   #11
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QuoteOriginally posted by SpecialK Quote
I shot multi for a long long time with mostly good results. One receny gray-day shoot came out a bit dark, so I followed Marc's recommendation about center, and tried that for about a month. Didn't notice a whole lot of difference, though I did go back to multi just a week or so ago....
Two main differences in my book:

1) Center-weighted is less likely to deliberately underexpose a scene just because of one small bright highlight. Conversely, of course, center weighted is more likely to blow the occasional small bright highlight :-)

2) Center weighted metering makes it more reliable to point into a shadow area, not the meter reading, then into a lit area, note the meter reading, and then set exposure accordingly. As long as the shadow and light areas I point to are reasonably large and take up "most"of the frame, I can be pretty sure my shadow metering reading is not being unduly affected by the light, or vice versa. I'll get a good read on the difference between the the light and shadow levels. With multi-segment metering, if there is *any* light area in the frame when pointing into the shadow, or any shadow in the frame when pointing into the light, chances are excellent I'll end up with the same meter reading in both cases, or at least reading that are much closer to each other than is correct.
06-03-2009, 01:50 PM   #12
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Thanks for the comments. I never used spot metering before, and I still don't fully understand how to use it, but maybe I just misunderstand you. It's said it's to be used with small objects, but from what I understood I would be able to spotmeter a few places (light, dark, grey, etc.) and then the camera would calculate a proper average. Is this possible on K20D?

Also, how do I operate it on the camera effectively? Do I point at something, half-press, then get the desired frame, then shoot? Manual focus? Autofocus? Etc., etc. Spot metering is really new to me (as is the K20D).

So far, multi-segment metering works fine for me. I assume this mode does average the scene.
06-03-2009, 02:17 PM   #13
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QuoteOriginally posted by Marc Sabatella Quote
I'm sure Pentax's multi-segment can be trusted to produce exactly the results it was intended to produce. That doesn't include reading your mind, though. And I don't really pretend to be able to read it's "mind":either. So I prefer center-weighted, because I *know* how that works and therefore how to get it to produce exactly the results I want every time.
That is exactly the difference between matrix-metering and center-weight: Matrix-metering is very reliable in about 80% of all situations. But if you shoot with strong backlight or with a lot of dark background etc., center-weighted metering is easier to correct with EV-correction, whereas with matrix-metering you never know, whether the logic analyzed the lighting situation correctly or not.

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06-03-2009, 02:58 PM   #14
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QuoteOriginally posted by Mann Quote
I never used spot metering before, and I still don't fully understand how to use it, but maybe I just misunderstand you. It's said it's to be used with small objects, but from what I understood I would be able to spotmeter a few places (light, dark, grey, etc.) and then the camera would calculate a proper average. Is this possible on K20D?
No, not the camera: *you* could calculate the average. Point at a white object, then a black one, then a medium one; one in light, then one in shadow, etc. Then figure out for yourself where in that that range you want exposure to be. Spot meter doesn't "save" up answers and then combine them for you - it simply reports the exposure necessary to turn the thing you are looking at into a medium value. Point at white, and you get an exposure that renders the white gray. Point it at black, and you get an exposure that renders te black gray.

QuoteQuote:
Also, how do I operate it on the camera effectively? Do I point at something, half-press, then get the desired frame, then shoot? Manual focus? Autofocus? Etc., etc. Spot metering is really new to me (as is the K20D).
Basically, if you don't have a really specific reaosn to use it, don't. It's an extremely special tool that requires you to know exactly what you are pointing at and why, and be able to do the "averaging" yourself if you wish to point at several objects.

Focus has nothing to do with metering (at least, nothing that is relevant here. Use AF or MF as you see fit; that's not relevant to this discussion.

QuoteQuote:
So far, multi-segment metering works fine for me. I assume this mode does average the scene.
Well, it doesn't "average" in any literal sense (eg, add up and divide by the number of segments). It does however try to come up with an exposure that it thinks might be appropriate for the scene as a whole, as opposed to spot metering, which completely ignores everything except the center and tries to make the object at center come out medium valued. And indeed, if often does a good job, but there will always be situations where it chooses an exposure other than you might have preferred. Most typically, by making the exposure too dark because it seems a bright highlight and it doesn't want that highlight overexposed, even though you probably would have preferred it did overexpose the highlight so the rest of the scene wouldn't be rendered so dark. So you learn to use exposure compensation to override the meter in those situations.
06-03-2009, 04:02 PM   #15
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QuoteOriginally posted by Mann:
I never used spot metering before, and I still don't fully understand how to use it, but maybe I just misunderstand you. It's said it's to be used with small objects, but from what I understood I would be able to spotmeter a few places (light, dark, grey, etc.) and then the camera would calculate a proper average. Is this possible on K20D?
QuoteOriginally posted by Marc Sabatella Quote
No, not the camera: *you* could calculate the average. Point at a white object, then a black one, then a medium one; one in light, then one in shadow, etc. Then figure out for yourself where in that that range you want exposure to be. Spot meter doesn't "save" up answers and then combine them for you - it simply reports the exposure necessary to turn the thing you are looking at into a medium value. Point at white, and you get an exposure that renders the white gray. Point it at black, and you get an exposure that renders te black gray.
Actually, there is (was) one camera I know of that did do multi-spot readings...the Canon T90. You could take up to eight spot meter readings, deciding what you wanted to emphasize in the scene (by taking multiple readings on it), de-emphasizing others (taking fewer readings). It was very nice. I miss it. *sniff*
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