I have a Industar 69. It's a great little pancake lens but it doesn't focus to infinity with the M39 adapter. The original camera it came with has a shorter registration distance than a normal M39 camera. Many people file down the lens to work. I rather try to make a smaller adapter. It looks like I should be able to take the M39 mount off a M39 camera as a base and then use a body cap to make it work. Has anyone done anything like this with a Sony body cap?