[Leica] RE: Tale of Two Telyts Part Deax - The Evil Twin

[rpalmier at depaul.edu (bob palmieri)]

Don Dory wrote:

Bob,
The Telyt is an achromat, only two colors controlled.  So, when examined
closely, you will see color fringing.  Until Canon started using 
flourite
and Nikon came up with ED glass and Leica started using glass with a 
lot of
flourite in it the Telyt's were about as good as it got.  Now it is 
better.


Don -

Thanks for posting up these facts-of-the-matter along with the 
historical perspective.  I know from the difference between APO & Achro 
in theory and I'm also pretty sure that this is indeed just a 
worst-case scenario that really makes the phenomenon graphically 
apparent.  So, here is my current thinking about this:

Firstly, it is quite interesting (to me, anyway) that a lens with this 
degree of CA (actually, thanks to Doug Herr for pointing out that it's 
more specifially referred to as Lateral Chromatic Aberration) produces 
such damn good imaging under normal circumstances.

Second, it seems that there may actually be some sample-to-sample (or 
years-of-production) variation among these lenses; because Doug  sez 
he's never seen it look this bad in any of his stuff.  (More reports 
from more users would certainly be of help in determining this.) If 
this is true, then anyone who's thinking about buying one of these 
things might wanna shoot a couple of quick digisnaps that include areas 
of quick transitions from deep black to bright white and ramp up the 
camera's display to an Actual Pixels magnification.

Thirdly, my goal with this kinda thing is to understand the tools as 
well as possible so that I can exploit their strenghts and minimize 
their foibles.

Gee... do you think I oughtta forward some of this thread to Uncle 
Erwin??

Bob Palmieri