Jupiter 8 (Kiev/Contax) to M39 Mod

thingiverse

This thing is a part to adapt a Jupiter-8 Kiev/Contax mount to m39. It’s meant to work with rangefinder cameras with little to no adjustments needed. Note as far as I know this will only work with a Jupiter-8, I’m unsure if it will work with any other Kiev/Contax Mount lenses. The reason I made this is because I bought a Kiev-4 that ended up breaking and I was left with a pretty nice Jupiter-8m that I couldn’t use on anything without a weird adapter. I really wanted to use this on an m39 body after I found out that there is an m39 version of this same lens, except that version is at least $40 compared to the Contax mount’s $20. It’s not a big price difference but there are way more m39 mount cameras compared to the amount of Contax copies that were made, plus I already had a Contax mount version. I tried to look for an adapter and I found a “Nikon RF to m39” print out: https://www.thingiverse.com/thing:4970535 but this was way too fragile and precise for my printer to handle. The only other adapters I found were a $300 kipon model and a $60 no-name one that had bad reviews. The helicoid I made will stop when it’s screwed towards the body, but there is nothing stopping it from coming unscrewed. You shouldn’t have to worry about this too much since the camera’s rangefinder will stop moving way before the lens is unscrewed. Instructions: 1. Print the two parts as they are positioned in the files (wide at the bottom skinny on the top). Use at least 10% infill or more and I recommend supports but you can get it to work without using them. 2. After printing take both halves and sand them to remove any stringy bits around the openings. 3. After sanding, take the “outer” part of the helicoid and screw it onto an m39 mount to clear any extra material in the m39 thread. Remove the “outer” half from the mount and set it aside. 4. Acquire a Kiev/Contax mount Jupiter-8 lens and take off the outer bayonet. There will be a single screw locking it in between the grip and bayonet. Take out that screw and proceed to unscrew the outer bayonet from the aperture ring. The lens will now look basically the same with a mostly black body and silver ring at the top, that’s as far as you need to go. 5. Next you will take the “inner” half of the helicoid and screw the lens into it. You want the aperture ring to end up being as close to the wide part of this piece, making sure you can still adjust the aperture. The lens should be nice and snug, there shouldn’t be any worry of it falling out. 6. Now take a small pea sized amount of vaseline and spread it over the screw of the “inner” half of the helicoid. 7. Finish it off by putting the two halves together and screwing it onto your camera body. Notes: If you are using this with an m39 rangefinder and your photos show up out of focus, you may need to adjust the rangefinder on your camera. I tried to model this as best as I could so that it would be accurate on a calibrated rangefinder, but there is still the off chance that it’s not sized perfectly. If you have other m39 lenses and your photos come out in focus then it might be an issue with the print. If you have the same issue with other lenses then you need to calibrate your rangefinder. I’ve linked a tutorial on how to do this yourself, note not all rangefinders have easy to access adjustment screws: https://www.youtube.com/watch?v=WnzqW8q-0D4 Some improvements that would be nice is a smooth helicoid and something to stop the lens from falling out. If I made the helicoid tighter than I’m worried that it wouldn’t print on lower quality printers and still end up working. And If I stopped the lens from falling out I wouldn’t be able to get macro shots on mirrorless bodies.