I'm hacking up an old TLR right now to put another shutter on it for zone plate work, and I'm wondering, how critical is the focal length for focusing. If I'm putting a 90mm zone plate on, but due to mechanical impediments it has to mount at 95 mm, how much of a difference will this make in the image.
Anyone know of some cheap SLR's that I can remove the lens but keep a functioning shutter? Like toy level prices? The Holga doesn't have the shutter speed range I'm looking for. Dwight
