Natural Vignetting

Hey guys, just a night photo with some vignetting. Can anyone explain to me how digital vignetting occurs and if you can control how much occurs. I'm interested in using it as an art form. This was shot with my 20d for 20 seconds.
thanks
andrew

Anyone? I could use some help.

I don't see any vignetting, I see natural gradation from a low-hanging sunlit sky transitioning to the night sky.

Vignetting is caused by lenses, typically when shot wide open.

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Originally Posted by drew2143

Can anyone explain to me how digital vignetting occurs and if you can control how much occurs...

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As one who vignettes most of my images in post-processing (see below), I can tell you it's much easier to control it in photoshop. Plus it's reversible...

Still, trying to do it in-camera can be an interesting challenge. One traditional method is to use a lens hood that is slightly too large for the angle of view of your lens. IOW, try say the hood for a 50mm lens with your 35mm lens.

Or, if you're really serious, get an adjustable lens hood like the Calumet/Lee system. Then you can fine tune the results.

I was referring to how the trees seem to blur. Is gradation what is causing that effect? I can't seem to find much information on the subject.

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Originally Posted by drew2143

I was referring to how the trees seem to blur. Is gradation what is causing that effect?...

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You said your exposure was 20 seconds. Anything moving in your scene is going to blur in the shot. And no, that's not gradation. Gradation is tonal. Although the motion blur can indeed cause a gradation, just not the other way around...

This isn't caused by movement in the scene. Look at the rest of the picture. The basketball hoop and one of the trees aren't blurred.

vignetting is the darkness around the edges of a photo caused by lenses or sometimes lens hoods if not using the right kind. most people add it in PP if they want it.

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Originally Posted by drew2143

This isn't caused by movement in the scene. Look at the rest of the picture. The basketball hoop and one of the trees aren't blurred.

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at the risk of sounding like a jerk, you're incorrect. Yes the basketball hoop isn't blurred, because it didn't move. same with one of the trees. from the looks of it, if this was shot on a 20 second exposure, and there's only that much blur, the branches weren't moving a whole lot, but they were swaying a bit. the thicker brances did not move, as well as all of the solid objects such as the bball hoop and the garage. It's motion blur from your objects moving, not from you moving the camera.

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Originally Posted by livin4lax09

at the risk of sounding like a jerk, you're incorrect...

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Hah, no risk here. I was about to say the exact same thing... :D

With a long exposure like that, the things that move during the shot will blur, the things that don't move won't.

The only other explanation is you had a big smudge on your lens...