ISCO V/S-Projar MC 2.5/90 projection lens

alex ph · Joined: 16 Mar 2013 Posts: 1614

Among projection lenses those having f2.5 aperture attract my curiosity, most probably being 5-glass instead of 3-glass formula, and thus promissing a more Planar-like IQ. This ISCO MC Projar must be the same as once reassembled by Ian, who found inside there 5 separate glass elements.

Having got this lens, I put it on a custom adapter that leaks bits of light. I tried to isolate some of them, but not sure if that was all successfull.

#1 A standard infinity test on Sony APS-C, pretty nice IQ, with some slight vintage touch

#2 Being compared to a Leitz Colorplan CF 2.5/90, it is left behind in terms of overall sharpness and contrast. Here is a Colorplan comparison shot

#3 A 100% unprocesed crop from Projar: strong CA and some softness are visible

#4 In close field this Projar, I'd state, is undistinguishable from very good Planars (APS-C shot)

#5 Converted to BW it shows an attractive character (a Sony FF shot)

I have intention to test it later at various distances and in real life situations showing more clearly the OOF / in-focus interplay. Still, those scarse test shots show that the lens clearly outperfoms many projection triplets in terms of shapes distinction and microcontrast, even if it does not render as crisp as Colorplan.

alex ph · Joined: 16 Mar 2013 Posts: 1614

The Projar had a kind of custom UV filter on that might differ the IQ. So, I took it off and put the lens on Sony A7 to be sure. I also equalized the game with Colorplan, this time with Made in Portugal P2 version. So, took consecutive shots under the same light conditions. Beside that, the light is grey and even, in some way ideal to observe lens rendering in details.

This time rendering test and the comparison are more correct. The new comparison does not change the Colorplan stronger contarst but shows that the difference is much less pronounced. And then, the Projar seems to keep a better corner sharpness.

Autocontrast is applied, except for the 100% crops which are left unprocessed.

#1 Projar

#2 Colorplan P2

#3 A 100% crop from the Projar shot (looks better if clicked)

#4 A 100% crop from the Colorplan P2 shot (looks better if clicked)

#5 Projar close-up

#6 Colorplan P2 close-up