At 18:30 1/15/01, Lex Jenkins wrote:
Here's a good example of bad bokeh. I can say that 'cause it's my photo.
;)
http://albums.photopoint.com/j/View?u=1005538&a=7400079&p=38140898&Sequence=0&res=high
CPC 28mm f/2.8 with six-bladed diaphragm. Macro-focusing, good resolution
and little distortion - but *ugly* bokeh. The caption explains it, but to
sum up it's the best/worst example of cross-eyed bokeh I've seen.
Hmmm, not possible for a single lens to be cross-eyed, but the likely cause
just came to mind. It's my educated guess your lens has astigmatism. The
best way to describe it is lines along one axis having a different focus
point than lines along a different axis such as horizontal versus
vertical. If memory serves me correctly, a lens with a cylindrical
component in its shape will exhibit astigmatism. If you were to take a
cross-section from the axis in the center to the edge, and rotate it around
the center, the cross-section would change shape. Astigmatism in a camera
lens will make it difficult to critically focus, except perhaps by using a
split image.
-- John
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