simonpg
Active Member
QG wrote earlier The pentagons are indeed a direct result of the pentagonal aperture.
QG, I agree but I was not suggesting that astigatism was causing the shape of highlight/bokeh - that would clearly be wrong. Sure these Zeiss lenses' pentagonal iris shapes (to the extent of how wide open they are and the actual lens' iris shape) logically create the outline shape.
Indeed my experience has been that one has to take some care with the light, optical traits and even specific lens' iris shape when out of focus is an important part of an image - they can lead to "ugly" effects that can be a big distraction.
My comments were generally in regards to the bokeh appearance (various factors drive that) and how astigmatism occurred in an image (the shifting or "ghosting" of a structure out of focus)I think Marc posted. Personally astigmatism is a trait I really dislike - maybe because I have astigmatism myself
I find the nicest bokeh seems to come from large format lenses which often have very circular iris apertures. The other day I was looking at a 1960s Zeiss lens for a Linhof 8x10 and there were so many blades I could not count them and the iris was so close to a perfect circle it amazed me.
QG, I agree but I was not suggesting that astigatism was causing the shape of highlight/bokeh - that would clearly be wrong. Sure these Zeiss lenses' pentagonal iris shapes (to the extent of how wide open they are and the actual lens' iris shape) logically create the outline shape.
Indeed my experience has been that one has to take some care with the light, optical traits and even specific lens' iris shape when out of focus is an important part of an image - they can lead to "ugly" effects that can be a big distraction.
My comments were generally in regards to the bokeh appearance (various factors drive that) and how astigmatism occurred in an image (the shifting or "ghosting" of a structure out of focus)I think Marc posted. Personally astigmatism is a trait I really dislike - maybe because I have astigmatism myself

I find the nicest bokeh seems to come from large format lenses which often have very circular iris apertures. The other day I was looking at a 1960s Zeiss lens for a Linhof 8x10 and there were so many blades I could not count them and the iris was so close to a perfect circle it amazed me.