I know I should post a picture or two here but I don't have access to a digiwhatsit and I'm curious as hell. Maybe somebody will enlighten me.
I've got a brass lens that has neither flange nor shade, like the magic lantern lenses I have do. It is about 4 inches long and is threaded at one end. I thought it might be a projector lens that fit into some track. It looks like a slide projector lens, but in brass and old. The funny thing is that inside the lens barrel is an aperture plate that has a hole of about 3 cm diameter that is not now fixed very well to the walls of the barrel. It appears that it might have been, but the marks inside the barrel do not give me a clear indication of its original placement. There is no slot for insertion or anything, it's just in there by friction and can be moved toward the front of the lens or toward the rear if you take out either front or rear cells and fiddle a bit. Is there an optimal placement for an aperture plate? Does it matter what the focal length of the lens is or is it a formula?
It's clearly an oldie, but the writing that was on the lacquer is long past reading. I put it into a 4x5 lensboard and, though I didn't get much chance to do a real test, it does not appear to cover 4x5 at infinity. Nice, sharp image, but it vignettes rather quickly. Kind of a large lens for medium format, but...
Oh hell, the more I write the more I realize I have to post some pictures...
I've got a brass lens that has neither flange nor shade, like the magic lantern lenses I have do. It is about 4 inches long and is threaded at one end. I thought it might be a projector lens that fit into some track. It looks like a slide projector lens, but in brass and old. The funny thing is that inside the lens barrel is an aperture plate that has a hole of about 3 cm diameter that is not now fixed very well to the walls of the barrel. It appears that it might have been, but the marks inside the barrel do not give me a clear indication of its original placement. There is no slot for insertion or anything, it's just in there by friction and can be moved toward the front of the lens or toward the rear if you take out either front or rear cells and fiddle a bit. Is there an optimal placement for an aperture plate? Does it matter what the focal length of the lens is or is it a formula?
It's clearly an oldie, but the writing that was on the lacquer is long past reading. I put it into a 4x5 lensboard and, though I didn't get much chance to do a real test, it does not appear to cover 4x5 at infinity. Nice, sharp image, but it vignettes rather quickly. Kind of a large lens for medium format, but...
Oh hell, the more I write the more I realize I have to post some pictures...
