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[OM] The end of onion-ring bokeh? Panasonic beats the curse of aspheric

Subject: [OM] The end of onion-ring bokeh? Panasonic beats the curse of aspheric lenses
From: Mike Gordon via olympus <olympus@xxxxxxxxxxxxxxxxx>
Date: Thu, 8 May 2014 20:03:19 -0400 (EDT)
AG writes:

The fact is that whatever is in focus is going to be more in focus
with a heavily corrected lens assembly whether aspherical elements
are
used or not.

Yes, very highy corrected, (some would label overcorrected for spherical aberation lenses produce funky bokeh whether they have apsheric elements or not--witness the excellent OM Z 50/3.5 with macro shots and a distant background. See the Dr. Nasse article again. In many respects it is a zero sum game.

http://www.smt.zeiss.com/C12567A8003B8B6F/EmbedTitelIntern/CLN_35_Bokeh_EN/$File/CLN35_Bokeh_en.pdf


If one optimizes for nice background bokeh , the foreground bokeh can get very busy and if spherical aberrations are too highly corrected lots of stuff happens including increased bright rings around the OOF bokeh highlights--to quote Nasse:

"....stronger counteractive measures towards spherical overcorrection strongly increase the brightness around the circumference of the circles of confusion:"

Now larger formats have a distinct advantage as the degree of blurriness in a distant background is a direct function of the physical size of the aperture. All that be said bokeh variables are highly complex and very dependent on the aperture, relative foreground/subject/background distances----is mentioned by Nasse as well.

I seem to agree with AG that apsheric elements do affect the drawing style or "rendering" of lenses but I'll defer to him on the reasons.

I recall Roger Cicala of Lensrentals has proposed ,----- 'render' is usually what lenses do when they do nothing else particularly well.
A bit harsh, I think.

Mike




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