NMFocal

The first of these two Isco lenses (on ebay) is quite massive and heavy.  Though it has very nice optics it is pretty impractical to use for most shooting scenarios for two reasons:   1) The size and weight requires serious lens support in the form of rods and brackets etc. There's no simple clamping solution for this one.  It's not a walking-around kind of anamorphic.  Good for telephoto shots on sticks.   Good for ballast on long ocean voyages.  Good for projecting glorious film prints (I'm assuming. I'm not a projectionist by a long stretch).   2) The minimum focusing distance is a whopping 17 feet. This lens was designed to throw a clear image from a projector onto a huge cinema screen at the end of a big room.  It is not designed to focus close!  The front element is very large as well, so most diopters won't fit.   The second Isco variety (like those that Vid Atlantic sells) are much lighter and focus as close as 5 feet (or even less at high F-stops on some taking lenses).  They are very sharp and impart very little contrast.  RIvals and sometimes beats a Kowa Bell and Howell (or at least my Kowa B&H)      This is my understanding of the differences.  I'm no expert but I've had several of these lenses and have used both types for shooting.