[Leica] RE: Tale of Two Telyts Part Deax - The Evil Twin (bob palmieri)

[hoppyman at bigpond.net.au (G Hopkinson)]

Bob, pardon me if this is a silly question.
Is this aberration definitely visible on the film?
(I assume its transparency film)
After your image is captured on film, obviously it must then be scanned to
produce your digital image for posting. I wondered if the aberration was
being introduced at that (weak link) point by the scanner?

Cheers,
 Hoppy
(who'd like a focomat in his coolscan)

-----Original Message-----

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Message: 20
Date: Thu, 6 Jul 2006 10:41:31 -0500
From: bob palmieri <rpalmier@depaul.edu>
Subject: [Leica] Tale of Two Telyts Part Deax - The Evil Twin
To: lug@leica-users.org, leicareflex@freelists.org
Message-ID: <0c6a689957fb15b7e15c496265b09547@depaul.edu>
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Folks -

As promised, here's an example of a disturbing symptom I encounter 
occasionally with the 400 Telyt.

Here's a snap of a blue heron impersonating a stick:

http://gallery.leica-users.org/album409/Camoflage_Heron_Crop


And here's a 100% pixel crop showing heavy purple fringing around the 
feet and along the top edge of the log (in areas of serious 
overexposure):

http://gallery.leica-users.org/album409/Camoflage_Heron_PurpleCrop


I've seen the same effect on Kodachrome, so I don't think it's one of 
those artifacts of digital sensor architecture (despite all the talk 
you hear about purple fringing in digicams.)  My questions are as 
follows:

1. Is this just a classic case of chromatic aberration in a simple 
achromat? (I hear tell that the Anomalous Dispersion glass (whatever 
that is) in this design is supposed to control this kindof thing to a 
pretty acceptable level.)

2. If so, is it really possible that the results in the normally 
exposed areas can look as good as they do (not that this snap is the 
best example; things were getting pretty dim at the time and the 
shutter speed was probably quite low) with a level of CA this high?

3. Does someone who uses both this lens and the probably staggeringly 
CA-free 280 APO (Doug??) ever see this effect in their 400 shots and 
not in those shot with the APO ?

Inquiring minds want to know...

Bob Palmieri


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