Topic: Pentacon AV 2.8/80 - the poor man's Trioplan ;)
I found this slide projector lens while cleaning my parent's flooded cellar and decided to do something with it
It is a simple triplet design, just like the Trioplan 2.8/50 & 2.8/100, it was even manufactured by Meyer Optik in Görlitz, which was, after joining with various other factories, renamed Pentacon by the early 70's. There is a longer version - Diaplan / Pentacon AV 2.8/100 - which is in fact the Trioplan's optics without an aperture mechanism in a plastic housing. My 2.8/80 is built in exactly the same way, very lightweight (<100g).
I adapted it using a plain M42-NEX adapter and some duct tape - it looks an awful lot like a remnant of a failed Mythbuster's project - but is in fact pretty sturdy. In this setup, it focusses between 0,3cm and 1,5m, which is nice for some dreamy flower-closeups or head portraits. I suppose, using a thinner adapter (LTM-NEX) could provide infinity focus.
Imagequality wise - it is okayish, pretty sharp in the image centre, some heavy halo or glow on sharp bits bits due to spherical abberation and - most important - the Trioplan's highlight discs with an accentuated outer rim.
some camera porn
larger: http://farm9.staticflickr.com/8413/8778 … 397e_o.jpg