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Old Jul 11, 2010, 7:41 AM   #1
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Default Setting exposure off the sky - for trees?

I've been messing around with my Peterson's Understanding Exposure book so I went outside and was hoping to get a photo of the blue sky and the green trees looking out my backyard.

I was in manual mode, photos taken at f/8 with various shutter speeds to get the exposure "correct."

The first picture is the sky, where I was setting my exposure. I then dropped the camera to include more of the trees, which is shown in the second photo. Then after seeing that the trees appeared too dark, I decided to just set the exposure according to the trees (at -2/3 "Mr. Green Genes" according to Peterson), and then the sky is no longer blue in the third photo.

I have a feeling this is a normal dilemna but what can I do to get a blue sky and a nicely colored green tree? I was dealing with morning light at about 8:30 am. Hmm, I'm puzzled.

I'm using a Canon Xsi with a 50mm f1.8.
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Old Jul 11, 2010, 7:54 AM   #2
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Use a GND.
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Old Jul 11, 2010, 8:11 AM   #3
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Use a circular polarizer.

Use HDR.
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Old Jul 11, 2010, 8:20 AM   #4
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Ok, I gotcha with the GND and the circular polarizer but what is HDR?

I'm shopping for an outdoor telephoto lens so perhaps when I'm at the photo store I'll check out some filters. I'm looking at the Canon EF 100-300mm IS USM and it looks like different filters sizes are needed for this telephoto and my favorite 50mm f1.8. But I suppose the 50 mm would be my inside/lowlight lens (which I dont think would need a filter) and then I could bust out the big boy for daytime outdoor shots with a filter.

Ok -thanks. I was curious as to whether there was an exposure trick to getting the shot I described above but it makes sense to try a filter.
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Old Jul 11, 2010, 10:30 AM   #5
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Your shot is beyond the dynamic range of your sensor. And you are right, it's a common problem. HDR is High Dynamic Range and refers to a way to extend the dynamic range - you take a couple of pictures - in your case it would be one exposed for the sky and one exposed for the trees and merge them together. There's software programs that can do it for you, or for simple things, you can do it yourself in photoshop/PSE using layers. All methods have their own advantages and disadvantages.

If you start buying filters, they can get expensive quickly. If you buy a really good CPL you might want to buy the diameter to fit your largest lens and then buy step-up rings to use it on your smaller lenses (I did that since I wanted a polarizer for a lens with a 77 mm diameter - gulp!). There's advantages and disadvantages to that, too, but it was a good solution for me.
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Old Jul 11, 2010, 11:54 AM   #6
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If you go with filters, get good ones. A cheap filter can cause more problems that it solves.
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Old Jul 11, 2010, 11:56 AM   #7
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You can go with a graduated neutral density filter, but it wouldn't work well in that particular scene. The graduated part is a straight line, and that image doesn't have a straight line seperating the sky from the trees.
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Old Jul 11, 2010, 3:37 PM   #8
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Quote:
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You can go with a graduated neutral density filter, but it wouldn't work well in that particular scene. The graduated part is a straight line, and that image doesn't have a straight line seperating the sky from the trees.
Actually, in my experience, a GND would be ideal for all but the first of these compositions. It is a mistake to imagine that a GND requires a clear line of demarcation -- if it did, it would be a very limited tool. In reality, anything that is roughly divided in half between too dark and too light will be well-served by a gradual GND. Try it and see.

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Old Jul 11, 2010, 5:18 PM   #9
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GND filters are most used in horizontal orientation, but they can be turned for the circumstances at hand. Graduated, means there is a gradual change from the dark to the light part of the filter, so there won't be a defined line showing where the filter changes. Often, and in this case, where the white of the clouds is behind the trees, the GND won't be as effective, and would probably produce something with dark sky, dark trees, and a light mid part along the demarcation. I would probably opt for bracketing exposures, and making a HDR. Alternatively, you could use the shot with the sky properly exposed and run it through HDR software to bring up the shadow detail. One of our board members, Martin Sykes, has created a very nice free application for this. Check out the HDR forum for the link, and some examples.

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Old Jul 11, 2010, 7:42 PM   #10
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GND filters are most used in horizontal orientation, but they can be turned for the circumstances at hand. Graduated, means there is a gradual change from the dark to the light part of the filter, so there won't be a defined line showing where the filter changes.
Just a terminological point. Graduated does not mean that the change is gradual. There are two kinds of graduated neutral density filters -- one is a sharply-demarcated filter with a dark half and a clear half. These are intended to be used in, e.g., photos of sunsets over the ocean, where there is a sharp horizon line. The more common (and more useful) GND is the gradual one. But both kinds are called "graduated neutral density filters."

As to the question of whether a gradual GND would be useful here, I can only say that I routinely employ them in just this kind of situation. I never use CP filters because I can never get them to do what I want. I typically get that awful artfactual sky with them. And, when I try using them in other settings, I don't seem to get the right amount of polarization set. I find the GND fool-proof, and I'm enough of a fool for that to be a pretty strong claim. I recognize that many people would use CPs on this kind of photo, and some of them would make it work. More of them would have a wierd artifactual sky and think they'd done a good job. Go figure.
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