I have to admit prior to the Delta 3200 thread today I haven't seen any practical examples of zone plate photography. I'm intrigued, particularly for (very) soft portraits. In SLRs I primarily use Pentax K-mount, but also have an M42 adapter. I also have an older Mamiya 645 that hasn't seen much use (by me, anyway). I've been searching around, but I don't see many options for pre-made zone plate body caps or longer focal lengths for these systems. I was able to find one for M42 here, and a Finney 150mm combination pinhole/zoneplate arrangement in K-mount here (which is a bit too expensive for me just as an experiment), and I don't see any for the M645. Are there other sources I'm missing?