Pentaxian Registered: November, 2011 Posts: 4,310 | | Review Date: September 15, 2013 | Recommended | Price: None indicated
| Rating: 7 |
| Pros: | Compact, reasonably sharp, very little geometric distortion | | Cons: | No modern coatings; can foul larger SLR mirrors at infinity | | Sharpness: 7
Aberrations: 8
Bokeh: 8
Handling: 8
Value: 10
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As far as I have been able to discover, this lens is a 1960s
plastic-fantastic version of a Schneider Curtagon 35/2.8,
with a simplified optical diagram:
ISCO, for Iosef Schneider CO, was closely related to
Schneider-Kreuznach. Despite the plastic in its construction,
the lens has held up well over its near half-century of
existence, and still functions nicely today.
The lens lacks modern coatings, but otherwise displays the kind
of optical excellence that could be expected from its Schneider
parentage. There is very little geometric distortion, CAs and
purple fringing are minimal, and the bokeh can be rather
pleasant. With the light behind you, you can rely on it to
produce quality images.
On the other hand, when strong light is
entering from the side or front, the lack of coatings may cause
loss of contrast and color, although nothing that a little
post-processing cannot normally recover.
When focused at a distance, the rear of the lens protrudes back
behind the lens mount. It fouls the mirror on a Spotmatic, but
my copy has now found a good home on a K-01. Second-hand
reports suggest that it will foul Pentax DSLRs (like the K7 or
K5) with a 100% view, but will clear the mirror of a K-x: I
have not tried this myself.
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