I picked one of these up for cheap recently. Impressive chunk of glass, for sure, and much to my surprise it seems to cover 4x5 pretty well. The Vade Mecum says it is a high speed lens for fluorography with the design based on triplet, 1+2+1+3. What exactly is flourography? The glass is tea colored, much like the radioactive Aero Ektars and I'm guessing it might be made of the same thorium glass. No iris, so it can only be shot wide open which is cool with me, and at f1.5 should produce some interesting results. Has anyone used one of these before? Any more info on flourography lenses?