[Leica] Colorplan, CF or FF?

["Anderson, Ferrel E" <AndersonF@ria.army.mil>]

I have used the colorplan CF lens for years with plastic and Kodak cardboard
mounts, and have been completely satisfied.  There is some variation in
sharpness between different slide mounts, but it is not critical, and it is
expected since the CF design is based on an "average" film curvature, which
means, aprioi,  that there will be variations that will affect sharpness.   I
have experienced unsharp zones in projected slides with the colorplan because of
the narrow depth of field of the f2.5 aperture of the lens no matter what kind
of mount I am using, but this has been because the projected image is not normal
to the screen.  Any tilting, whether it is left and right, or up and down,  will
result in unsharp zones in a left and right or up and down orientation,
respectively. 

90% of the time, though, my projected slides with CF lenses are sharp.  For
critical work I use glass mounted slides and flat field lenses, and am planning
on buying a Super Colorplan lens to use for glass mounted slides in my
professional slide shows.   If one is projecting a mix of glass mounted slides
and plastic and cardboard mounted slides, a flat field lens is preferred.  Ever
project a glass mounted slide with a CF lens?  Talk about unsharpness!

I have determined the resolution of the Colorplan CF lens   It resolves 117 l/mm
across the field on its curved field.  This is outstanding, and I expect better
performance from the Super Colorplan.  I think that with the improved
performance of modern films, the Super Colorplan is needed.  Leica states that
they have offered the Super Colorplan to transfer the improved performace of
their APO lenses to the screen.   I think that modern Leica lenses at their
optimum apertures have been able to outperform many films, but the new APO
lenses probably do this at more apertures, and for this reason also the Super
Colorplan is needed for best performance.

Ferrel Anderson