Archived posting to the Leica Users Group, 2007/10/12

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Subject: [Leica] George: 28mm Summicron IR problem
From: imagist3 at mac.com (Lottermoser George)
Date: Fri Oct 12 15:59:49 2007
References: <7FA6647D-A36C-4A86-84B3-A4756DA8FB77@comcast.net> <673C7DEC-A9C1-490A-8F6F-821246CF27FC@comcast.net> <00db01c80d21$88b0d030$6101a8c0@jimnichols>

Having attempted to deal with these "hot spotted" images in a number  
of different ways; I think it would be a poor use of time to attempt  
to correct it with blocking in the optical path.

For a brief period I considered the possible use of a center weighted  
filter. But once you see how "hard" this hot spot is; and without  
contrast; it becomes fairly evident that any available center filter  
would not work. You'd have to go through mind numbing tests; looking  
at all sorts of various "donut" configurations in the image to come  
anywhere close to a "block" correction. And even if you could get  
there and correct for the "over exposure" you'd still have to deal  
with the lack of contrast in that  "spot."

Regards,
George Lottermoser
george@imagist.com



On Oct 12, 2007, at 5:45 PM, Jim Nichols wrote:

> I've been following this thread, but since I have none of the  
> equipment involved, haven't said anything.  In looking at Tom's  
> comment, it occurred to me that it might be interesting to try a  
> blocking center spot applied to the filter, similar to the approach  
> used with one of the early Leica lenses.


Replies: Reply from len-1 at comcast.net (Leonard Taupier) ([Leica] George: 28mm Summicron IR problem)
In reply to: Message from len-1 at comcast.net (Leonard Taupier) ([Leica] George: 28mm Summicron IR problem)
Message from tomschofield at comcast.net (Tom Schofield) ([Leica] George: 28mm Summicron IR problem)
Message from jhnichols at bellsouth.net (Jim Nichols) ([Leica] George: 28mm Summicron IR problem)