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Old Jan 28, 2008, 12:33 AM   #1
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I took some pictures of a winter sunrise. The histogram showed two rather thin skyscrapers, on both sides of the center of the histogram screen. I played with the exposure up and down from -1 to +1 in thirds but still got the same histogram. what does it mean and what should I do?
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Old Jan 28, 2008, 12:56 AM   #2
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No problem there. I assume the left clump is the ground and the right is the sky? Not all histograms have to be all filled out. It just so happens that you were taking a picture of something with two prominent values. As for getting the proper exposure, you're just going to have to go with what looks best. Could you perhaps post the photo?
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Old Jan 28, 2008, 12:57 PM   #3
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What happens in the middle of the histogram is irrelevant! It's when it touches the right or left side that you're in trouble. Touch the right side and you've blown the highlights, touch the left and you've buried the shadow detail.
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Old Jan 28, 2008, 2:21 PM   #4
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doto41 wrote:
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I took some pictures of a winter sunrise. The histogram showed two rather thin skyscrapers, on both sides of the center of the histogram screen. I played with the exposure up and down from -1 to +1 in thirds but still got the same histogram. what does it mean and what should I do?
The histogram shows what is happening within the dynamic rangeof the photo. Manipulating the exposure just picks up the histogram and shifts it to the left or right. The actual values represented by the left and right side of the histogram change as you adjust the exposure, but what happens within the range remains the same.
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Old Jan 28, 2008, 7:51 PM   #5
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I agree with all of the above: what you have is just what is expected.
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... and what should I do?
You don't have to put up with the expected. Ding about with contrast and gamma, or if they are available to you, use curves and levels.

You should be looking to dig out any details available at the ends of the distribution. Things like subtle shading in the snow which is likely blown out (can't do anything about that - everything is stuck at 255) or nearly blown. by stretching the right peak you might be able to recover some detail.

However, simple techniques are likely to force the dark areas (left side of the histogram) to pure black or zero.

Ding about, figure out your editor, and ask more questions as things go on.
___________
Another way to deal with this issue is dealt with via HDR (High Dynamic Range) messing about. Search the forums here or take a look at http://www.luminous-landscape.com/tu...blending.shtml for an old and excellent tutorial on the subject.
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Old Jan 29, 2008, 11:14 AM   #6
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TCav wrote:
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doto41 wrote:
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I took some pictures of a winter sunrise. The histogram showed two rather thin skyscrapers, on both sides of the center of the histogram screen. I played with the exposure up and down from -1 to +1 in thirds but still got the same histogram. what does it mean and what should I do?
The histogram shows what is happening within the dynamic rangeof the photo. Manipulating the exposure just picks up the histogram and shifts it to the left or right. The actual values represented by the left and right side of the histogram change as you adjust the exposure, but what happens within the range remains the same.
Of course, the "twin tower" histogram may alsoprompt you to consider digging out your GND or taking two photos at two different exposures for compositing later in PS.
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Old Jan 30, 2008, 11:41 AM   #7
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what is 'GND'?
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Old Jan 30, 2008, 5:17 PM   #8
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doto41 wrote:
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what is 'GND'?
Graduated Neutral Density filter. See http://en.wikipedia.org/wiki/Graduated_ND_filter
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Old Feb 1, 2008, 10:10 AM   #9
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TCav wrote:
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Graduated Neutral Density filter. See http://en.wikipedia.org/wiki/Graduated_ND_filter
Hi TCav,

I read that article.Are polarizing filterssignificantly different other than they cover 100%? It appears they affect a photo similarly in the filtered area.

Dennis
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Old Feb 1, 2008, 10:40 AM   #10
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erutcip wrote:
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... Are polarizing filterssignificantly different other than they cover 100%? ...
Neutral Density filters (not Graduated Neutral Density filters)reduce the amount of light passing through to the lens and camera. They areuseful if you want to take a long exposure or use alarge aperturefor abrightlylit subject. Graduated Neutral Density filters reduce the amount of light passing through to the lens and camera for a portion of the image, while letting all the available light pass through for another portion of the image.

Polarizing filters are different. They reduce the intensity of very intense light (from haze, glare or reflections, such as those from the surface of water), andthereby increase the color staturation for lessintensely lit subjects.

While Neutral Density filters reduce the intensity of all light, Polarizing filters only reduce the intensity of very bright light.

See http://en.wikipedia.org/wiki/Photographic_filter
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