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03-18-2008, 04:23 PM   #1
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Metering 101 Question

I made the change from P&S to DSLR last October, and have learned a lot just from reading these threads. With that being said, I'll put myself out there with what must be a BASIC question, hoping someone besides myself has wondered this in the past!!

I now somewhat understand the 3 metering modes on the K10, and even found the dial to switch them My question is difficult to articulate, however here goes, in several parts!

It seems Metering is used to determine correct exposure, yes?
And, it seems that depending on if you are in M or TV or AV, etc .. you can adjust certain parts of exposure with the e-dials.
From what I read in the posts, people Meter then decide what exposure settings to change.

Ok, here's the silly part .. how do you read that meter reading?? Is there some display I am not seeing on my camera?? I feel stupid even asking, but hopefully someone can clear this mystery up for me!!

03-18-2008, 04:41 PM   #2
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"Reading" in this case means interpreting what the camera is suggesting as ISO, shutter speed and lens aperture. Depending on the value you give to "freezing" the action or how much "depth of field" you need, you will either increase or decrease any of those variables to get the result you are looking for, e.g. increase shutter speed to freeze movement or decrease it to leave a trail behind the moving subject, or closing the diaphragm (from a small number toward a larger one) to have a "deeper apparent zone of sharpness". It takes a little bit of time to learn to do it by habit, but after a while, it kind of become second nature. Try to use your camera more often on manual mode and change the parameters and examine the results while checking the "exif" will help to figure out what works and what doesn't for a given situation. Hope you can figure out something out of my explanations.
03-18-2008, 05:44 PM   #3
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Flyer's comment is spot on. Get out in the field and play with the settings. At least with digital you don't have to want for your film to come back from the lab. But, I'll try and comment on what I've learn and read.

I was reading about this last night in a book on nature photography I picked up from the library and it had some pretty solid advise about metering. First off, everything on your K10D exposure is centered around stops. With a stop being a measure of the amount of light reaching the sensor. The exposure compensation is also in stops. EV +1 = increase exposure one stop from what is recommended from the program line (what the camera calculated based on how much light came through the lens). Assuming spot metering (which I am liking more because it gives me more control) where ever you put the center of the view finder is what is metered. The camera assumes this is a "medium" amount of light (18% gray if memory serves) and adjusts the exposure settings accordingly.

So, to set an "correct" exposure you just find a part of your shot that you judge to be this light intensity and you get an exposure that that part of the image being the middle of the light intensity range. But, let's say you want that part of the picture to be "light," increase your exposure by about 1 - 1.5 stops from the exposure setting that the camera returned. This is easy do do in manual mode. Point the light meter to your spot, press the green button to get the camera's opinion and then adjust your aperture, shutter, or ISO to give you one more stop. On the light meter in the view fined (where the exposure compensation normally shows) you'll see that your spot not reads as one major tick mark to the right (positive), showing that you are 1 stop away from the middle exposure. What it lighter? Add another stop. Darker? subtract.

Outside of manual mode you can do the same thing with exposure compensation. Exposure lock on the spot you want to control and add or subtract EV units as necessary. Notice that the shutter or aperture will change accordingly. For Ts and Av modes I've set one of the edials to exposure compensation do I can do all of this in the view finder and don't have to press another button. In any mode the histogram is a very good litmus test for your exposure.

I'm still learning myself, but these are the basics as I currently understand them. Hope that helps. As said just playing around, thinking about light, and how to control it is the key. If you want some reading I'd personally recommend "Understanding Exposure." It gives a very clear and practical explanation of this very topic.
03-18-2008, 06:09 PM   #4
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There is NEVER a stupid question! If you don't ask, how will you ever learn the answer?

The mode you choose is usually determined by what you are shooting. Every setting (aperture, shutter, ISO) has advantages and disadvantages...in photography, it's always give and take. Sometimes it's easiest to explain by example so here goes...

I shoot mostly landscapes with a K10D. I usually don't care about capturing fast action. I'm concerned mainly with getting as much detail as possible, large depth of field (as much of the picture in focus as possible), and precise exposure control to capture as much color as I can.

With this said, I almost always shoot in manual exposure mode (that "M" on your dial). I then do the following:

1) Select the ISO speed that will give me the best quality. This is almost exlusively ISO 100 for me. In laymen's terms, the larger the ISO number, the faster the film and you can catch more action. But as you get larger on the ISO, you also get grainier pictures. Very low ISO will get sharp pictures, but you will need a very slow shutter speed which means any movement from your subject will blur.

2) Select an aperture setting that gives me the most depth of field but doesn't cause diffraction (pixellizing). The larger the f/stop number, the greater the depth of field, but also the better chance you will reduce image quality with pixelizing (depends on the lens where this will start to be noticeable). The smaller the f/stop number, the less the depth of field. I usually pick something around f/16 or so.

3) Select the shutter speed that will give me the exposure I need (meter). After I have selected ISO speed and aperture, it's simply a matter of looking in the viewfinder and rotating the shutter speed dial until the meter centers. When that happens, theoretically I have metered for proper exposure. Of course, I may end up over or under exposing a little to get the exact picture I want. Proper exposure by meter alone does not account for the human factor...that is, personal taste, artistic intent, etc.

Hope that helps! The best thing you can do is practice and experiment. Flyer is right in recommending that you use manual mode as much as you can to learn the techniques. Happy shooting!

03-18-2008, 06:38 PM   #5
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Hi Idelude, welcome to the forum.

One of the best exercises my photography teacher had us do to understand metering, was to photograph shadows.

Here is the exercise, great to do on a sunny day:

1. set the camera to spot meter.
2. meter for the center of a shadow, and take a picture. The shadow will come out grey, and washed out. The sunlit areas will be over exposed
3. meter for the sunlit area beside the shadow. Use the meter lock, and retake the same picture. This time the shadow will be dark, and the sunlit areas will be corectly exposed.

so simple. Kind of makes sense. What is the point?

The point is that the camera has no idea if you are taking a photo of a bright scene with dark areas, or a dark scene with bright areas. To the camera, it is just taking the spot where you told it to meter, and it sets the exposure as if that area is a medium grey. It is up to you to decide where to best meter, lock the exposure, and take the picture.

It took me awhile to trully get this.

Eric.

Last edited by KungPOW; 04-28-2008 at 05:35 PM.
03-18-2008, 11:16 PM   #6
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Thanks everyone!

Really good info .. I forgot to say that I have a pretty good understanding of how shutter speed/aperture/iso work, independently. I've been taking courses at betterphoto.com, and they've been EXTREMELY helpful. (for any newbies out there, feel free to email me if you're interested in more info on those)

I'm just starting to learn how all these come together, and now I am beginning to grasp the concept of how (a) my camera can meter for me, and (b) how I can adjust the exposure settings. You have given me some great take-aways and practical applications, so now it's up to me to try it all out and take it to the next step!
03-19-2008, 05:20 AM   #7
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I second the recommendation for "Understanding Exposure" book. I just got it from Amazon and even with my 20 years of picture taking adventures, it is still a good read. Never thought of comparing film ISO to bees
03-19-2008, 05:52 AM   #8
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Hi Idelude,

I, too, highly recommend the Bryan Peterson book "Understanding Exposure." There were many "light bulb going on moments" for me while reading that. It is great help to anyone and especially a beginner as I am.

My photos are still pretty poor but thanks to that book my exposure is almost always spot on. Now I just need to work on composition and creativity to make them rise above a well exposed snapshot. LOL

Robin

03-19-2008, 08:01 AM   #9
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OP - you read the light meter through the viewfinder. it looks like something like this: <--|--|--|--|--|--> the edials (depending on what mode your in) will control the shutter speed and/or aperture.

QuoteOriginally posted by KungPOW Quote

1. set the camera to spot meter.
2. meter for the center of a shadow, and take a picture. The shadow will come out grey, and washed out. The sunlit areas will be over exposed
3. meter for the sunlit area beside the shadow. Use the meter lock, and retake the same picture. This time the shadow will be dark, and the sunlit areas will be corectly exposed.



Eric.
the following may be a bit much for a 101 question.


Your camera's light meter reads 18% gray. That's what it uses to determine 'proper' exposure. Nice medium. It will overexpose scenes with lots of blacks and underexpose scenes with lots of whites. It reads those extreme tones as grey and that's why you see a lot of gray snow shots and in your first example gray shadows. what you should ultimately try to set your exposure to is a middle tone in the scene. In your example shot, I believe if you metered for the gray sidewalk, you would have come up with a better exposure, like your second shot.

if your in matrix metering (metering the entire scene) and shooting in manual, you should evaluate the scene for heavy blacks or whites and adjust what your light meter reads accordingly. Most often I don't even find this necessary.....

If your shooting in some type of program mode, you should familiarize yourself with exposure compensation. underexpose scenes heavy with blacks and over expose scenes heavy with whites.


QuoteOriginally posted by rzarbo Quote
Hi Idelude,

I, too, highly recommend the Bryan Peterson book "Understanding Exposure." There were many "light bulb going on moments" for me while reading that. It is great help to anyone and especially a beginner as I am.

My photos are still pretty poor but thanks to that book my exposure is almost always spot on. Now I just need to work on composition and creativity to make them rise above a well exposed snapshot. LOL

Robin


Get that book!!!! Its a great book. I read it after shooting for almost a decade and still learned a few new things.
03-19-2008, 12:37 PM   #10
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Wow! This book comes highly recommeded, there are so many out there, I tend to avoid them all (terrible habit, I know). I live by testimonials, so I will definitely give this one a shot.

Thanks all!
03-19-2008, 01:03 PM   #11
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Not to split hairs...

But the fist shot is intentionally over exposed. It is to show how the camera's meter will over compensate if you meter from an area that is too dark for the scene.

The second shot was metered from the bright area beside the shadow. ie the sidewalk.

Eric
03-19-2008, 01:18 PM   #12
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QuoteOriginally posted by KungPOW Quote
Not to split hairs...

But the fist shot is intentionally over exposed. It is to show how the camera's meter will over compensate if you meter from an area that is too dark for the scene.

The second shot was metered from the bright area beside the shadow. ie the sidewalk.

Eric

no doubt! My intention was to try to explain why the meter does that!
03-19-2008, 05:13 PM   #13
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QuoteOriginally posted by jshurak Quote
no doubt! My intention was to try to explain why the meter does that!
Oh! My misunderstanding. I thought you were expaining to me how not to get a photo like in example one.

I really should not post during my lunch hour. I think the lack of air in the boardroom left me "cognitivly challenged"

Eric.
04-20-2008, 12:31 AM   #14
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QuoteOriginally posted by drabina Quote
I second the recommendation for "Understanding Exposure" book. I just got it from Amazon and even with my 20 years of picture taking adventures, it is still a good read. Never thought of comparing film ISO to bees
QuoteOriginally posted by rzarbo Quote
Hi Idelude,

I, too, highly recommend the Bryan Peterson book "Understanding Exposure." There were many "light bulb going on moments" for me while reading that. It is great help to anyone and especially a beginner as I am.

My photos are still pretty poor but thanks to that book my exposure is almost always spot on. Now I just need to work on composition and creativity to make them rise above a well exposed snapshot. LOL

Robin
...another vote for Understanding Exposure. I had so many "light-bulb moments" that I was starting to get giddy. Very good book.
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