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Old July 2nd, 2011, 11:44 AM
Bart_van_der_Wolf Bart_van_der_Wolf is offline
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Quote:
Originally Posted by Nick Masson View Post
Thanks for the replies. It seems, then, that there is little use in stopping down to f/22 or so unless your composition includes a subject quite close to the lens (5 to 10ft).
Hi Nick,

The unsharpness that's added as a veil over the entire image is directly related to the F-number. The F-number itself is a ratio of focal length and aperture diameter (therefore also written as f/#), and is the most important factor in determining diffraction blur. Small apertures, therefore large F-numbers, produce a lot of diffraction blur.

Distance is only important for the Depth of Field (DOF) blur at certain distances away from the plane of focus.

Quote:
Asher and Doug, would you suggest any literature about optics resolution, and particularly hyperfocal technique etc... It is something that has always interested me.
One of the most accurate on-line descriptions can be found at:
http://toothwalker.org/optics/dof.html and
http://toothwalker.org/optics/dofderivation.html

And of course Doug has written a paper about the subject, but his webpage seems to be not responding right now.

Cheers,
Bart
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