Thread: Metering
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Old 04-03-2008, 07:43 PM
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LandonW LandonW is offline
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Well I am not that familiar with the Olympus e510. I took the quote below from the Olympus website for the e-510.

"Get a great shot in any lighting situation with five metering modes including spot metering and the new 49-point ESP Meter."

It sounds like you will have program modes for sports, portraits, macro etc.. in the auto mode. You should have at least three manual modes with spot, center and multi or "49-point esp meter."

I will address manual metering here because the automatic modes are mostly self explanatory and come with cool icons. The best resource on these auto modes is in your manual.

The setting most people will leave their cameras on is the multi metering mode. This means you are telling your cameras processor to measure the light across multiple areas of the cameras sensor. The processor will decide what tonal values to expose for. For example, if you have 60% or more of your composed frame in the shade and the rest in full sunlight your sensor will try to capture the exposure for the shade while still trying to get a descent exposure for the sunlight areas. Sometimes this is impossible due to the dynamic range of the sensor. More often than not it will split the difference between the light and dark. If you have a majority of your composed frame in a low light situation then your camera will expose for that.

Center weighted metering: The camera will only measure the area in the center of the frame. This includes more area than spot metering. What this does is allows you to have measurement for a selected part of the frame. I tend to use this if I want to expose specifically for a subject in the frame and only that subject. You could say it's kinda the reverse of using your headlights in your car. With Multi metering you are using your brights to see everything. With center weighted metering is like using your low beams, and spot metering would be like using a flash light. Usually you will have to point the center of the viewfinder to the subject you want to expose for. Then you adjust your exposure to what the meter suggests for that subject. Let's say you have a person that takes up the left third of the frame. In center and spot metering mode you would point the center of the view finder to the area of the person you would want a good exposure for, the face. Then you would look at the display in the viewfinder to adjust your exposure settings. Since I don't know the olympus I can't give you a lot of detail about your readout in the viewfinder. Usually you will see a + and - icon with varying levels of bars pointing to each one. When in Center or Spot metering mode it will give you real time feed back. So let's say you have the center of the viewfinder pointed at your subjects face and it's displaying full bars to the - sign. The sensor is telling you three things in no particular order:

1. Change your ISO.
2. Adjust your aperture.
3. Adjust your time of exposure.

You can change one variable or all of them to get the best exposure for that tonal value.

What the camera is telling you is to let more light in.

1: ISO, If your camera is set to 100 ISO then you could change it to 400 or 800 or any step in between to get those bars to move to the middle. Here is where you control "grain" or noise. The artifacts that appear because the limits of the sensor are being reached at higher ISO.

2: Aperture or F stop, The shutter that limits the amount of light passing through the lens to the sensor. By opening the fstop you will be able to get the bars over to the middle ground and a more acceptable exposure. Here is where you control depth of field. The larger the opening or smaller fstop number the less depth of field. That means if you have to open up to f4, or wider, then you will have less area in focus.

3: Shutter speed, the length time the shutter opens to allow light to strike the sensor. By increasing the time the shutter stays open you will be able to move the bars in the view finder to the center and thus a better exposure for the face. Let's say your camera was set at 1/500sec. You could dial down you shutter speed to something like 1/60th sec or any step between until you see the exposure meter bars getting closer to the middle.

Spot metering is the extreme of Center weighted metering. It gives you much more control over measuring certain areas of your frame. I rarely us this mode, if there is an area that needs special attention and that extra TLC to get the best exposure then I might use this. If you get to the point of using grey cards to calibrate your camera then you might want to learn about this mode. For now I would forget about it.

I would do some research on aperture priority, shutter priority and then set some time aside for bracketing a subject. Bracketing means you take multiple shots of your subject with different camera settings. Usually you start taking photos either under exposed or over and work towards the opposite. You usually expose one stop over/under the "correct exposure." One stop means doubling or halving the amount of light hitting the sensor. You can bracket with any of the 3 variables above. I would suggest doing only one variable at a time. This way you can see the effects for each variable and understand those factors. It isn't very common to bracket with ISO. I try to keep the ISO as low as possible to get the least amount of noise. Think of ISO as your last choice to increase the sensitivity to light of the sensor. When shooting sports this conditions changes and the higher ISO's are necessary to capture at faster shutter speeds.

Too much info?

Sorry

I tried to condense as much as I could, I hope it helps.
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