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

[don.dory at gmail.com (Don Dory)]

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
don.dory@gmail.com


On 7/6/06, bob palmieri <rpalmier@depaul.edu> wrote:
>
> 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
>
> _______________________________________________
> Leica Users Group.
> See http://leica-users.org/mailman/listinfo/lug for more information
>