Helios 44-2 to Nikon-F conversion kit

Simple kit to adapt the legendary Helios 44-2 M42 lens to fit Nikon (D)SLR bodies. It's possible to easily achieve infinity focus due to the Helios specific design.

Disclaimer

Be careful to not protrude the lens too deep into the camera body to prevent collision with the camera mirror. I am not responsible for any damage to the lens or camera.

This adapter will not work with different lens types due to a bug in the Biotar/Helios mount design. If you're looking for generic M42 to Nikon-F adapter, use this one.

Make steps

• Print the mount adapter part. Either PLA or PETG should work just fine. Use the finest layer height your printer can print. Enable elephant foot compensation - the tolerances are tight. Use dark filament to prevent unwanted reflections inside of the camera chamber.

• Optionally apply some lubricant to the adapter thread.

• Use this lens cap by @StepanBroz_131676 as a handle to screw the adapter onto the lens. It should not be possible to tighten the adapter with a bare hand. If it is, your printer is probably under-extruding.

• Test the fit on your camera. You could have perfect infinity focus by now if you're lucky. If not, continue to the next step.

Calibrating for infinity

The actual dimensions differ from lens to lens. This is due to soviet manufacturing tolerances. The infinity calibration could be measured and calculated. It is, however, easier to approximate as follows.

• If the lens can't focus to infinity, scale the helicoid shim model down by one percent along the Z axis only and print it.

• If the lens focuses beyond infinity, scale the shim up by one percent along the Z axis only and print it.

• Unscrew the lens assembly off the helicoid part (see the pictures). There should be an aluminum shim similar to the one you've printed in the previous step.

• Replace the shim and screw the lens back into the helicoid.

• Test and repeat the process if the infinity focus is still not good.

CAD design files @Onshape

Happy shooting!