Archived posting to the Leica Users Group, 2001/05/04
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At 8:30 PM -0500 5/4/01, Rodgers, David wrote:
>I had some sharpness as well as exposure
>issues. Diffraction may have been the culprit. I try not to go beyond f11.
>Even that may be stopping it down too much.
A common rule of thumb states that you shouldn't use an aperture
smaller than the focal length divided by 4 if you don't want to lose
out to diffraction. By that rule the 15 shouldn't be used stopped
down to more than 5.6 and the 12 is hopeless by definition (or lack
of it ;-)). For outdoor shots that has tiny detail in the distance I
don't stop down smaller than f/8. However, since one of the uses that
I got these lenses for is photographing architectural models, the
diffraction limitation is actually a bit of a benefit. If you look
closely at these models, even the ones costing $50,000, there are a
lot of rough edges and detail is obviously lacking at the finest
level. So shooting at f/16 or f/22 even gives me an even level of
'smoothed out' lack of resolution that acts like a Softar for
portraits. Pinhole photography at its finest!
- --
* Henning J. Wulff
/|\ Wulff Photography & Design
/###\ mailto:henningw@archiphoto.com
|[ ]| http://www.archiphoto.com