It's an interesting concept. I had a Konica to Nikon adaptor that I enabled me to use an old Konica TC body with my Nikon lenses. The camera store clerk who sold it told me it was a waste of money - would never work. He was largely wrong.
I think you'll find the pin is a diaphragm actuator which, when pushed, closes the lens to the desired aperture setting. The adapter will probably push the pin in all the time, so that as you select an aperture setting less than maximum, the lens will stop down immediately.
you'd only be able to use lens that have the manual/auto switch, and would have to switch to manual metering or AV mode. Most like the metering would not be as effective stopped down to f16 or so. That's what I've found with my Pentax cameras and screwmount lenses anyway. I'm interested in trying it on a Nikon FE, which is designed for stop down metering.
If you're talking about an M42 to Nikon adapter, they exist, but in order to achieve infinity focus, have an optical element (which may or may not degrade performance - almost certainly does). Of course it also entails stop-down metering and a completely manual diaphragm.
I have one (came with a lens I bought), but never tried it.
IMHO you are much better off using your M42 lenses on a Spotmatic.
If you're talking about an M42 to Nikon adapter, they exist, but in order to achieve infinity focus, have an optical element (which may or may not degrade performance - almost certainly does).
Are you sure, the one's i've seen on eBay, don't seem to have a negative internal element.
I'm going to be using one with a 42 - 39 double thread adapter, so I can mount a 12 mm Voigtlander in to an underwater lens housing. This only takes Nikon mount lenses. I use 2 Tamrons right now.
The lens only has to focus to between 1 - 1.5 ft. The lens is focused on a virtual image due to the dome shape of the lens housing, used with wide angles lenses.
Are you sure, the one's i've seen on eBay, don't seem to have a negative internal element.
I'm going to be using one with a 42 - 39 double thread adapter, so I can mount a 12 mm Voigtlander in to an underwater lens housing. This only takes Nikon mount lenses. I use 2 Tamrons right now.
The lens only has to focus to between 1 - 1.5 ft. The lens is focused on a virtual image due to the dome shape of the lens housing, used with wide angles lenses.