I just received a totally mint Nikon F Photomic FTN for $79 and of course it requires a battery conversion for modern day non-mercury batteries. So I put a piece of Delrin rod, a very good hard plastic that machines well and that I've used for other photo applications, in my metal lathe and machined the outside diameter down to fit inside the battery chamber. I then bored a hole in the center to accept the ZA675 batteries that will work as replacements. In the top edge of the cylinder and part way down the side I cut a groove and placed a strip of thin copper in it so that it would touch the small contact point in the battery chamber to complete the circuit. The copper strip also extends into the center of the battery and with the compartment cap in place, presses down on the battery to maintain contact. Checked it out against another meter and it seems to be right on. I had this model of camera back in the late 70's and then it was stolen. It will be great to once again shoot a classic Nikon that I really enjoyed back then.