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04/19/2006 01:37:17 PM · #1 |
This is going to be hard to explain...
The center of your DOF, or the distance from your lens where items will be in focus, is it a plane perpendicular to the front of the camera lens, or is is a fixed distance from the camera lens, resulting in a curve.
Example, I'm taking a photo of a brick wall with a wide angle lens and a large aperture resulting in a very shallow DOF. I'm perfectly perpendicular to the brick wall.
A. If the center of DOF is a perpendicular plane, the wall would be in focus across the entire photo, even though the edges of the wall in my photo may be several feet further from the camera then the center of the wall.
B. If DOF is a fixed distance from the lens, the wall on the edges of my photo would be out of focus because the wall would be beyond my DOF.
Anyone know which it would be?
Thanks
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04/19/2006 01:41:59 PM · #2 |
You explained that very well.
I'm interested to hear the answer to this, too. |
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04/19/2006 01:42:02 PM · #3 |
In theory the lens is corrected so the DOF is in fact a perpindicular plane. In practice, some lenses are way better at this than others. It's one of the major issues in the design of ultra-wide-angle optics.
R.
Message edited by author 2006-04-19 13:43:32.
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04/19/2006 01:42:48 PM · #4 |
pretty sure it's a plane perpendicular to the lens
but
most lenses are less sharp towards the outside, giving the appearance of an out of focus edge
Message edited by author 2006-04-19 13:43:25. |
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04/19/2006 08:40:52 PM · #5 |
Originally posted by Bear_Music:
In theory the lens is corrected so the DOF is in fact a perpindicular plane. In practice, some lenses are way better at this than others. It's one of the major issues in the design of ultra-wide-angle optics.
R. |
Rob,
Here's a great example: //www.16-9.net/lens_tests/14mm/14mm_test_3.html
(The whole comparison starts here if you're interested: //www.16-9.net/lens_tests/14mm/14mm_test.html ) |
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04/19/2006 08:48:26 PM · #6 |
What Robert refers to is called "field curvature." It's not easy to control, and many lenses have it to some small degree. It's more common on WA glass, but it shows up quite commonly in some telescope designs as well. Most telephoto lenses designed for cameras have pretty flat fields, however.
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