Archived posting to the Leica Users Group, 1997/07/27

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Subject: Re: M-lens question
From: Dan Cardish <dcardish@microtec.net>
Date: Sun, 27 Jul 1997 20:29:12 -0400

At 04:48 PM 27-07-97 -0700, Roger wrote:
[snip]

>Flare and coma are much better in the ASPH compared to the regular 
>Summilux. My biggest reason for owning it.

You may well be right.  Maybe it says something about the lighting
conditions in which I primarily do my photography, but I have never
considered either coma or flare to be a major problem with the standard
35/1.4 Summilux at f-stops 2 or below.  The one time I encountered what
appears to be really bad coma (or spherical aberation;  I'm not sure how to
distinguish the two) was when I photographed the Northern Lights during a
famous power outage in Quebec about 10 years ago. A nearby hospital had
it's own power sources, and window lights showed significant asymetrical
flaring.  I was shooting at f1.4, though.

I have noticed that point sources of light appear very sharp at f1.4 with
the aspherical.  One should be carefull when photographing point light
sources to test for coma, etc.  It is east to overexpose point light
sources, in which case, it is possible for the focused light to "spread" a
bit into the emulsion, giving the impression of some kind of optical
aberation. 

Dan C.