I just looked this up as I used a M39 Helios-44 with my K100D with M39->M42->PK setup.
Borrowed my own text from the
Helios-44 thread:
Originally posted by ovim I've learned that Leica M39 has register distance of 28.8mm and Zenit M39 has exactly the same register distance as the Pentax/Praktica M42 (45.46mm). The thread on the Leica M39 is also of different pitch (M39x26tpi vs Zenits M39x1mm). I googled a bit and found a third M39 mount which is Braun Paxette M39. It has the same M39x1 thread as the Zenit but register distance is only 44mm so no infinity focus with this one.
edit: I quess the difference of the thread pitch i neglible because the adapters are sold as Leica and M39 compatible
There seems to be different versions of M39 Jupiter-9
This I found from
Manual Focus Forum :
"There are a least two types of silver Jupiter 9. One has an M39 screw fit mount, has one aperture ring, and is intended for rangefinder cameras (Zorki, Fed). A second, again with an M39 mount, has two aperture rings - one to preset, and a second to stop-down. It was intended for early SLR cameras (Zenit C(S)). The lens registration on the first differs wildly from that required for the normal M42 distance and, as Ballu indicates, a lot of engineering is required to make it useable on an SLR. However the registration on the second is only out by a fraction of one mm (if at all) and the lens can easily be converted into M42 with the aid of a simple adapter ring."
So no go with Leica or rangefinder Jupiters