Isco PC-Ultra-AV 45/2.8
Multicoated slide projector lens for Kodak Carousel with perspective correction. Black metal body marked Isco-Optic. AKA Meridian PC 45/2.8.
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For a slide projector lens, the Isco PC-Ultra-AV 45/2.8 has an uncommonly sharp Zone A (centre frame): 8.45 near field. It’s also uncommonly heavy (649g) – and to achieve infinity focus you almost need to glue the barrel to the lens mount. If the shift mechanism is desired, at least 25mm of the 52mm diameter plastic barrel must be trimmed and clamped to a short M42 helicoid. Note that the given focal ‘flange’ distance of 67mm refers in this case to the distance from the rear element to the camera sensor, not the end of the barrel as supplied.
The combination of chunky perspective-control rings (likely brass) at the front and a plastic barrel at the rear makes this lens cumbersome and front-heavy. I therefore recommend a different method of adaptation. The optical assembly unscrews from the shift housing via what looks like the front element retaining ring. The business end of the lens weighs just 368g with glass close to both ends of the aluminium tube measuring 37mm diameter and 110mm in length. The front now sports a useful 62mm thread which requires a rear-mounted step-up ring.
Before mourning the loss of a shift mechanism, know that the Isco PC 45’s movement isn’t the familiar ‘straight up and down’ type. As a taking lens, the circular travel is actually something of a nuisance. Personally I find it better to fit enlarger and projector lenses with suitably large image circles on M42 shift and tilt adaptors.
The 45/2.8 certainly has a large enough image circle, and it works very well on full frame with generic M42 tilt and/or shift adaptors, or bellows systems. The only mod needed is to affix an M42 helicoid or M39 > M42 adaptor to the rear barrel, which is conveniently stepped, allowing a good contact area for epoxy resin bonding (see gallery pictures for details).