OT -- KolariVision Astro-photography cover glass, Sony a7r, Leica glass
2016-06-11 by roark.paul@...
This is not related to printing, but for B&W shooters from the film days who liked Kodak Tech Pan's extended red sensitivity, this might be of interest.
I had my Sony a7r converted with this astro photo cover glass and have posted the first comparison shot on page 2 of my PDF on this project. See
http://www.paulroark.com/BW-Info/KolariVision-Astro-BW.pdf
The Loxia was on an un-converted Sony a7r2.
As the graphs on the PDF show, "Tech Pan's" extended red sensitivity characteristics are very close to the Kolarivision astro filter.
The astro filter is thinner than the OEM cover glass. As a result, Leica M wides work quite well at f/8, but still have a bit of un-sharpness wider.
The WATE (Wide Angle Tri-Elmar 16-18-21) plus the astro filter may be quite a landscape combo; my interests being B&W.
The astro cover glass is very incompatible with the Zeiss Loxia 21mm made for the Sony. The advantages of optics designed for the specific cover glass characteristics are obvious, and not much glass is, in my view, likely to be made any other way going forward.
The thinness of the astro cover glass was a surprise. It shot down my hope of using the Loxia and it's very good f/2.8. However, with the WATE (and other Leica glass at f/8) the old Sony may be very interesting.
(This was also distributed to the LUG.)
Paul