Archived posting to the Leica Users Group, 1997/01/04

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Subject: 35mm ASPH and coma???
From: Michael Hintlian <102144.2651@CompuServe.COM>
Date: 04 Jan 97 09:25:16 EST

Someone in here posted a note in the past few days about buying a 35mm Summilux
ASPH and having a problem with coma. (Was it you Dan C.?)  They then sold the
lens and bought another that didn't have this problem.

Something troubled me about that post and I'm sorry I didn't jump on it
then...but I will now.  My first question is how did the user identify the coma
problem...what method of test demonstrates coma or "no coma" in this lens?  What
was looked for?  What measure was used?  How does the author define coma?

If the coma was truly there, why wasn't the lens returned to Leica as defective?
It was a new lens was it not?  I'm certain if this lens had this quality
especially one that Leica went to such trouble to perfect that they would have
remedied the problem post haste.  Of course, they would have wanted to test it
(and Leica has that capability in Northvale) and if it were found to be
defective, it would have been replaced.  My experience has been that they never
resist when an item has a flaw and will promptly make a replacement.  Was this a
grey market, non-USA lens? 

I'm very much interested in hearing exactly what criteria was used to determine
the coma problem.  In practical use, how does one know coma when they see it?

Appreciate your response...whomever you were.  Thanks.

Michael Hintlian