[Leica] Problem summicron uniformity

[dorysrus at mindspring.com (Don Dory)]

Chris,
The most probable cause of the side to side unevenness is your shutter
capping at higher speeds.  To test this, open up your camera with the
lens off pointing the camera at an even light source.  Start tripping
the shutter at say, 1/60, and work up to 1/1000.  If all is well then
you will see an even band of light.  If all is not well then you will
see an uneven opening as you describe in your post.

A good CLA will fix this.

On the other hand, if the ASPH has had a really good knock and one of
the elements is out of alignment then you can get some strange effects
including uneven lighting of the frame.  What you describe would be
almost impossible to occur, but almost is not not.

Last, in some really bizarre twist of lighting and defective filter
pointed at just the right angle to the sun, you could see some flaring
that would act like a strip ND filter.

So, take the filter off, load some cheap C-41 film in your camera, point
it at a clear sky or some other even toned subject, and take some snaps
at a fixed EI.  Process the film and look at the film.  If it is the
lens, you should see some weird exposure patterns.  If it is the
shutter, at some speed you will start to see a graduated film density.
If it was the filter then you will see no change as you don't have the
filter on.

Hope this helps.

Don
dorysrus@mindspring.com



-----Original Message-----
From: lug-bounces+dorysrus=mindspring.com@leica-users.org
[mailto:lug-bounces+dorysrus=mindspring.com@leica-users.org] On Behalf
Of Saganich, Christopher/Medical Physics
Sent: Wednesday, December 08, 2004 12:28 AM
To: Leica Users Group
Subject: [Leica] Problem summicron uniformity


Hello

I took my leica to the beach with my summicron ASPH 35 and Orange/red
filter.  The shots all have noticable nonuniformity side to side.
Darker on the sides then in the center by about one stop. 

Example:
http://www.apug.org/gallery/showphoto.php?photo=4185&password=&sort=1&ca
t=500&page=1

I went back over other rolls and noticed the same thing even with my M2,
but didn't notice this with other lenses.  I made a few test shots with
my Voghtlander 35/2.8 with same filter and then made an identical shot
with the ASPH Summicron 35, then without the filter.  Similar patterns
were observed for both lenses but less so without the filter.  

The question is whar should I expect from these lenses in terms of
exposure uiformity?  Is there a mechanical Issue with the shutter?  Do
filters cause these issues?

Thanks,

chris

 
 
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