Re: [APML] Reducing Coma

[Roland Roberts <roland@astrofoto.org>]

>>>>> "William" == William R Mattil <wrmattil@ix.netcom.com> writes:

    William> I don't see how it would hurt. I normally stop the lens
    William> (any lens) down at least one stop anyway. With the types
    William> of lenses that I can afford this is usually
    William> mandetory. :^)

Well, I don't either (other than the pain in the neck the next day
from bending over the eyepiece to manually guide and the longer
exposure time from stopping the lens down).  I figure I'm going to try
it.  I was just hoping someone could chime in with personal experience
or a knowledge of optics that said "yes, it does/sometimes helps."

I have never touched a lens that didn't need to be stopped down at
least two stops to get a good focus.  But this is the first time I've
used this particular 135mm lens and I was surprised that the only
aberration visible was coma.  My 50mm lenses show some very strange
distortions when wide open at f/1.4.

roland
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