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04-02-2010, 08:43 AM   #1
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Struggling with metering, k200d

Is there a failsafe method of getting a roughly correct exposure.

I mean a way, that might be somewhat crude and approximate, but fast and will ALWAYS result in usable exposure. 1 EV error would be very good.

Currently i'm using SPOT mode. CW and MULTI makes hard to understand what you're compensating for and what the mode has already taken care of.

Still, often i run in situations where in SPOT mode i get readings withing several EV even with plain white snow in overcast day. Which spot needs +2EV then? If being careful (+/- 0.7EV max) i often end up with under exposure.
If being conservative, you could probe the whole scene, decide what needs to be correctly exposed, take few DR test shots and get the correct exposure.

In reality, especially with people, you have to get the shot instantly. Not necessarily nail the exposure, but black silhouettes wont do.

Thank you.


Last edited by ytterbium; 04-02-2010 at 08:43 AM. Reason: typo
04-02-2010, 09:02 AM   #2
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Remember that as far as your spot meter is concerned, everything is the same colour as a gray card, so if you are going to use a spot meter, you have to accept that you will be biasing your exposure, often by several stops.
Snow scenes, especially when combined with overcast, present problems, they will cause any meter to under expose, since the meter is trying to bring the scene back to gray.
The old school way was to use the "sunny 16 rule", which allowed for shooting without metering.
It worked quite well with limited range slide films, I expect it will also work with the extended range sensors that we are now using.
04-02-2010, 09:04 AM   #3
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I would definitely NOT be using spot.
04-02-2010, 09:46 AM   #4
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Thanks.

Well for the snow, i already told that i'd be using +2EV as a rule for it. But what use +2 has if you can read values with 5..6 EV difference from the same white looking snow.

You find some sort of average white then? Or hunt for the highlight? One of them obviously will give you 2..3 EV error. Should the snow be +2EV of what you want to be correctly exposed or else?

Those are the kind of questions im trying to avoid, because they dont go well toughener with fast shooting and will result in rushed and erroneous exposure.

QuoteQuote:
I would definitely NOT be using spot.
Why not? Other modes are even worse, i think. If one of the segments catches a +20EV highlight in a 3 EV average scene, with 1 EV blacks, it will calculate the average exposure value to something like 8..11 EV. And you will have no idea what value has it metered from such highlight to compensate it.

04-02-2010, 10:40 AM   #5
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Spot mode is for people who alreayd completely understand metering and know how to take the extra steps required in order to use spot mode - virtually every shot you ever take using spot mode will require either metering then hitting AE-L and recomposing, exposure compensation, or both. Sounds like you're basically on the right track there, but if you're not getting exactly the results you want, there must be a gap in your understandng somewhere. I suppose you could simply work on that, and practice until you really get the hang of it, but still, that seems a very special-purpose way of working, and msot people are better off with more general-purpose ways.

If you just want decent exposures right out of the box, use either of the other two modes- they are meant to produce decent results with no extra steps except in specific cases (backlit subjects, etc). That should get you within 1 EV of where you want virtually every time.

My basic method is to use center weighted mode, which I'll use in basic P&S mode much of the time (compose, meter, and shoot). But when I want more control over the results, I mentally divide my scene into light and shadow, meter each separately (perhaps pointing at a light or shadow area completely outside the frame if necessary to find a relatively uninterrupted expanse of each type of light), and set the exposure so the shadow rside reads negative, the light side positive, and *I'm* in control of whether I bias for the light or for the shadow.

And my real quick-and-dirty method of dealing with the common case where I have backlit people and I just wna thtem exposre well and couldn't care less about the background - meter off the group at my feet. Maybe back a click or two from there if I want *some* chance of not blowing out the background. I can do this fast enough that it's essentially like using P&S.
04-02-2010, 10:46 AM   #6
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QuoteOriginally posted by ytterbium Quote
Well for the snow, i already told that i'd be using +2EV as a rule for it. But what use +2 has if you can read values with 5..6 EV difference from the same white looking snow.
That doesn't happen if your camera is working properly and you really are metering off the snow. At most, you'd be seeing 1 EV variation or so - and seldom that. Assuming you're not trying to compare snow in light to snow in shadow, that is.

QuoteQuote:
Why not? Other modes are even worse, i think.
Other modes are designed to give "reasonable" results just by pointing and shooting, unless there is a bright light source in the scene. So in those particular scenes, compose with the light source not in the frame, meter, lock exposure, then shoot. But even that worst case scenario is far easier and far more reliable than using spot meter, as you yourself are discovering. Spot metering is *not* a good general purpose metering method.
04-02-2010, 10:52 AM   #7
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The short answer and simple example from me is:

If you use spot and someone is wearing a black and white checkered shirt, and your spot segment is on the black, everything will come out overexposed. If it's on the white, everything will come out underexposed. So even a teensy weensy one-inch pan/turn of your camera will result in RADICALLY different settings.

Spot is such a narrow metering area (just a spot!) that if you had it on a woman's deep red lipstick, it would screw up the entire face--because the lipstick is way darker than the pink skin.

You tend to use spot for smaller objects far away, like a bird against a bright blue background, where you want to totally eliminate any exposure considerations for the sky--you just want to get the BIRD properly exposed.
04-02-2010, 11:42 AM   #8
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QuoteOriginally posted by ytterbium Quote
Thanks.

Well for the snow, i already told that i'd be using +2EV as a rule for it. But what use +2 has if you can read values with 5..6 EV difference from the same white looking snow.

You find some sort of average white then? Or hunt for the highlight? One of them obviously will give you 2..3 EV error. Should the snow be +2EV of what you want to be correctly exposed or else?
Our snow has pretty much all melted, so I can't step outside and do spot readings but....

Snow in deep shadow might, in order to be exposed correctly, have to be set to Zone 4 or perhaps even lower (-1 or -2 exposure compensation), while some in very bright sunlight moght be as high as Zone 8 or even 9 (+3 or +4 exposure compensation).
If you really want to use a spot meter, research the Zone System of exposure.

QuoteQuote:
Those are the kind of questions im trying to avoid, because they dont go well toughener with fast shooting and will result in rushed and erroneous exposure.
Spot metering is not suited to fast shooting.

QuoteQuote:

Why not? Other modes are even worse, i think. If one of the segments catches a +20EV highlight in a 3 EV average scene, with 1 EV blacks, it will calculate the average exposure value to something like 8..11 EV. And you will have no idea what value has it metered from such highlight to compensate it.
A good multi-segment metering system will not make the types of errors you are proposing in that many situations, though it is certainly within the realm of possibility that you have had some metering failures depending on the type of pictures you tend to shoot.
I still find the best metering method is center weighted. It biases the exposure towards where we tend to put the subject, and with judicious use of exposure lock (or just shooting manual exposure with green button insta-adjust), it is easy and quick to secure correct exposure.

Also, if you use your camera on manual, you can pretty much just wander around taking pictures as long as the light conditions don't change, and with a little effort it becomes quite easy to learn what conditions require an amount of compensation from your baseline of the moment.

04-02-2010, 12:24 PM   #9
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Unfortunately pressing backspace while editing resulted in browser back action, so all my pretty answer goes to trash....how i hate when it happens.

To keep it short. Thanks for help. I had no idea the spot meter was so narrow, i is the whole area between the round central brackets.
I almost always get underexposure with plain sky. Is 18 % that dark? It sure isnt pretty looking exposure. In sunny days i must meter shadows to get proper looks.

It might be helpfull if you could advise me how would you meter in pictured situations. Pardon the boring contents, they were just for testing. I included exif, told where i metered and what i wanted:


Exposure: 0.003 sec (1/320)
Aperture: f/7.1
Focal Length: 200 mm
ISO Speed: 100
Exposure Bias: +0.7 EV
Exposure Program: Program AE
Metering Mode: Spot
Metered as seen on image. The heli had to be brighter, including the whole sky.


Exposure: 0.013 sec (1/80)
Aperture: f/5.0
Focal Length: 70 mm
ISO Speed: 100
Exposure Bias: +2 EV
Exposure Program: Program AE
Metering Mode: Spot
Metered from one of the brightest portions i could find in the seen image.
The snow should not be completely blown (even in raw).


Exposure: 0.003 sec (1/400)
Aperture: f/8.0
Focal Length: 70 mm
ISO Speed: 100
Exposure Bias: +1.7 EV
Exposure Program: Program AE
Metering Mode: Spot
Metered from the plain white snow to the lower right from image center (between straws).
Its 0.7 or more EV too dark.


Exposure: 0.02 sec (1/50)
Aperture: f/7.1
Focal Length: 70 mm
ISO Speed: 250
Exposure Bias: +0.3 EV
Exposure Program: Program AE
Metering Mode: Spot
Metered from the center of image.
Snow should not be blown. Trees are not as dark as heli shot.

The set:
http://www.flickr.com/photos/39614026@N05/sets/72157623631936177/(full exif, 640x423px images)

Last edited by ytterbium; 04-02-2010 at 12:29 PM.
04-02-2010, 01:42 PM   #10
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♦♠I don't know what to tell you, other than spot metering is as much art as science.
I would have used center weighted metering for all of those scenes.
The helicopter looks about right for what you did. An 18% gray card is quite dark, and there is no guarantee that your light meter is colour blind, so the sky colour might be throwing it off a bit as well.
The deer droppings just plain looks like an over exposed picture. In this case, you should probably have trusted your meter.
The third picture is getting closer to what would be considered a normal scene, and you've underexposed it by a stop or so.
The last picture, you should have biased a bit on the under side, since the what you metered on is in shade, hence the meter is overexposing.

I noticed the last picture still had the exif data intact, and you have your contrast set to hard. This lessens the exposure range that is available, and you are shooting some pretty long range scenes (the helicopter being the exception), so you might be knocking the camera when you are actually setting it up to fail.

Last edited by Wheatfield; 04-02-2010 at 06:29 PM.
04-02-2010, 02:35 PM   #11
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The +2 EV comp is for center weighted or matrix metering. Using it in spot mode will blow out the snow every time. I have the 200D, and it will do a better job for fast, general photos with center weighted metering.
04-02-2010, 02:52 PM   #12
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What happens is, when the spot area targets on something, it THINKS it's 18% grey, treats it that way, and the meter makes its recommended exposures BASED on that. It doesn't matter if the sky is bright daylight blue, or burnt orange dusk. And it doesn't matter what you want it to look like--the meter only sees reflected light.

For every example you posted, if you had placed an 18% grey card in the scene (impractical, of course) and spot metered on that, you would have perfect exposure. Otherwise, with spot, you metered at 2% grey, or 50, or God knows what--but the camera is still treating it like 18. (Bad, dumb camera!)

Center weighted simply takes an average reading of the center, where most subjects lay, and multiple takes an average of everything.

This average is going to deliver, always, more consistent and correct exposure throughout the entire frame.

Last edited by Ira; 04-03-2010 at 07:00 AM.
04-02-2010, 03:34 PM   #13
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I'd say those shots are *excellent* examples of why we're all saying spot metering is *not* a great general purpose metering option. It requires slowing down to be sure *exactly* of what spot you are metering as well as the experience to be able to judge how much compensation might be needed for each and every possible surface you might choose to meter from. Unless you already know *exactly* what you are doing and don't mind working relatively slowly even then, this just isn't what you should be using, because it leads to exactly the results you are seeing.

In the case of helicopter off the sky, you metered off the sky, which therefore came out about 18%, and the helicopter darker - just as I'd expect. *If* you could control the spot precisely enough to make sure it only metered off the helicopter and not the sky, this would be fine. But in practice, it's going to much easier to make the quick determination: is that helicopter in light or shade, then meter off something similar on the ground. And unless you match the exact value of that helicopter, you'l do better with center-weighted because it will meter off the *average* of the different values in that same light.

For the droppings, you are right that overexposing a spot meter reading on snow should not have blown out the snow with only +2 compensation; I guess without seeing the scene you metered off, it's hard to say. I can only guess you didn *not* in fact meter off one of the brightest areas - or something dark appeared in the scene and thrrew off the calculation. That's the danger of trying to base an entire scene on a small value. Averaging a larger area is *much* less likely to lead to these kind of errors. In any case, as you can see, this is going to be a tricky scene no matter what, because if you exposed much darker, those droppings are going to clip to black.

The next image looks exactly as I'd expect given how you said you metered - apply 1.7 stops compensation to an area leaves it about a full stop shy of white, and that's what I see here. I'd have simply center weighted the scene itself, maybe added half a stop to compensate for the fact that it is lighter than average as a whole.

In the last shot, you metered off the trees which would have exposed them well (although you pushed it by dialing in positive compensation, thus rendering them lighter than they should be, as trees are generally not lighter than 18%). So as it is, your trees came out a little lighter than they should have - just as you asked - and the much lighter snow is blown out in comparison. In other words, you got exactly what you should have. I'd have center-weighted the trees, then double checked that against the snow, and if I saw the snow more than a couple fo stops brighter (which seems likely), I'd have dialed back to keep the snow from clipping. Or center weighted the whole scene and then added half a stop to a stop or so to compensate for all that snow
04-07-2010, 08:58 PM   #14
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One has to know the basic between spot, centre-weight and matrix metering before one used them to his/her benefit in photography.

I do agree with Marc's assessment on spot metering. The "examples" on spot metering by ytterbium are good for all to know. Generally spot metering is "not a good" general purpose metering option as it requires "stepping" down on which spot you are metering as well as the experience to be able to judge how much compensation might be needed for each and every possible surface you might choose to meter from. For eexamples, the sky, snow, beach etc.
04-08-2010, 12:07 AM   #15
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I'll use spot metering as an exercise, or if I have the time for it and no opportunity for my time-tested method, which is: center-weighted and aim down. In my film years I either hand-metered or used cameras with simple center-weighted metering, and I found that I nearly always got usable results in contrasty situations by metering off the ground near me, or off my hand or sleeve. In other words, find something that looks about 18%-grey reflective, meter off that, and use that exposure for your shot. If a subject is quite light or dark, I may adjust the exposure to suit, but metering off a nearby neutral object has saved my butt many many times. And now you can automagically bracket without burning up film. Miracle!
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