Re: [APML] Reducing Coma

["William R. Mattil" <wrmattil@ix.netcom.com>]

Roland Roberts wrote:
> 
> Last month, I tried some shots with a couple of "new" 135mm lenses I
> bought off Ebay.  I had already done focus tests using a Hartman
> mask---even the New York City lights don't prevent getting a decent
> focus test from something as bright as Arcturus.
> 
> I took a couple of test shots at f/4 of Delphinus.  On one camera I
> seem to have not tightned down the attachment sufficiently as I have
> some obvious flexure that created trails.  On the other I have a
> radial pattern of trails that looks like coma.  I think the lens is an
> f/3.5 (I'm not at home and can't check right now).  Am I likely to be
> succesful at reducing the coma by stopping down the lens?

Roland,

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

Regards

Bill

-- 
William R. Mattil	| Fred Astaire wasn't so great.
wrmattil@ix.netcom.com	| Ginger had to do it all backwards
(972) 399-4106		| and... in high heels.

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