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Old Feb 13, 2007, 7:31 PM   #1
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Photo challenge..white on white



With the recent snows a lot ofthe UShas seen this week, I thought it might be a good opportunity to have a WHITE ON WHITE challenge. This is a repeat challenge from February 2004. And of course snow and ice need not be the subject.

The challenge is to use lighting and metering and be able to tell one white subject from another. Another way to distinguish between white is texture and hue.

I know I am not that comfortable with the use of metering so I am going to take this opportunity to stretch my abilities with my camera.



"



As always, two posts per day, two images per post.



Happy shooting!
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Old Feb 14, 2007, 11:18 AM   #2
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Thanks! Great challenge! Nice photo. I remember this one from the last time around.
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Old Feb 14, 2007, 11:30 PM   #3
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Rather than explain a metering phenomenom numerous times I will explain it here.

When using auto exposure (program mode, shutter priority, aperture priority), the metering system will always yield an image that is equivalent to a sheet of 18% gray paper. Most of the time, this works fine. However, when shooting bright or all white scenes or very dark or black scenes, the meter will yield the wrong exposure. In the case of a bright or white scene, the meter will darken the exposure to 18% gray. In a dark scene, the meter will lighten the exposure to 18% gray.

To overcome this problem with the metering, we use exposure compensation. Exposure compensation allows you to increase or decrease the metered exposure by a specified amount. In the case of a bright scene, it is necessary to use positive compensation. Start with a compensation of +1.0 and adjust up or down depending on the resulting exposure.

With a dark scene, you would use a negative compensation. Start with -1.0 and adjust as required.

Basically what this all means is that if you are shooting a bright scene, you need to open the lens an f-stop or more and for a dark scene, you need to close the aperture an f-stop or more. It sounds odd but it is true. Remember, this technique is only needed for automatic exposure.

Cal

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Old Feb 15, 2007, 1:22 PM   #4
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Cal, this is going to be a great help, thank you.



Now, I have a question about a situation I ran into this week. Would metering have helped in this situation, dark auditorium with bright stage lights on stage, many brightly colored costumes, several white ones? I had several performances to play around with settings. Should I have increased or decreased the metered exposure?
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Old Feb 15, 2007, 6:38 PM   #5
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Hi Vanessa,
If you are close to the stage, you shouldn't have to do anything special except possibly adjust white balance. If you are farther back in the auditorium and can zoom in to fill the frame with the stage, again, no problem. However, if shooting from the back of the auditorium and the stage doesn't fill the frame, I would recommend using either spot or center weighted metering. If you use normal program mode, the areas of darkness will affect the exposure and the stage may be too bright.

Note, don't try to use flash from the rear of the auditorium. It won't have any effect on the image and may make some people very upset!

Hope this helps.

Cal

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Old Feb 19, 2007, 11:53 PM   #6
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Hi Cal,

I think the exposure compensation works opposite from what you suggested. Abright scene (lots of light)requires negative compensationto reduce thelight going in, thus preventing over exposure, while a dark scene (less light)requires positive compensation (more light) to prevent under exposure.
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Old Feb 20, 2007, 1:32 AM   #7
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Tullio wrote:
Quote:
Hi Cal,

I think the exposure compensation works opposite from what you suggested. Abright scene (lots of light)requires negative compensationto reduce thelight going in, thus preventing over exposure, while a dark scene (less light)requires positive compensation (more light) to prevent under exposure.
No, Cal explained it right , although I might suggest starting out with a +1/3 or 2/3 exp comp. for a bright scene and see if that works instead of a full +1, but it's digital, so all it costs is time...
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Old Feb 20, 2007, 1:30 PM   #8
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Hi GoCubs,

Maybe I'm not understanding what it is meant by bright/dark scene. So, let me change the terminology to over and under exposed scenes instead. To me, an over exposed is a bright scene and to correct that, one needs to set the Ev to a negative value (-0.3, -0.67, etc.),while an under exposed is a dark scene, which can be fixed by increasing the Ev value (+0.3, +0.67, etc.). At least, this is how my H1/FZ20/D40 cameras work. Now,perhaps the EV implementation is different in other brands/models, I don't know.
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Old Feb 20, 2007, 2:41 PM   #9
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Calr, your post was a great help. I've always wanted to do something like this, so this gave me the necessary knowledge to make my shot.
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Old Feb 20, 2007, 7:24 PM   #10
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Cal's explanation is 100% correct. Bright scenes like snow will fool the camera and it will under expose, you will notice grey snow, by boosting the ev you will get white snow not a over exposed shot.

Bob
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