Pentacon Six (P6) -> Canon EF Adapter

WARNING: DESIGNED FOR USE WITH A METAL CANON EF BAYONET ONLY

This is my attempt at a Pentacon Six to Canon EF adapter, created because spending 40–70 euro on a simple mechanical spacer feels like daylight robbery. Fully plastic adapters technically work, but I do NOT trust plastic bayonets (especialy 3d printed ones) with heavy medium-format glass.

This adapter is designed to be used with a metal Canon EF bayonet.

Mine was taken from a broken Canon 24–105L lens. A partial .STEP model of the EF bayonet I used is included for reference.

If you have a broken Praktisix/Pentacon Six body, you can reuse the original lens locking clamp. If not, I reverse-engineered my clamp and included it in the .STEP and .STL files as well.

To achieve true infinity focus, the adapter length must be 30.10 mm, measured from the P6 locking surface to the EF bayonet mounting face.

Required Parts:

-Canon EF Metal Bayonet (IMPORTANT):

Metal ring height: 3.350 mm

Measure your own bayonet (preferrably with a micro meter) before committing to my dimenions, if your bayonet differs, you must adjust the model accordingly (towards inside of the body itself) to maintain infinity focus.

-Original EF bayonet screws or equivalent screws that sit perfectly flush (protruding screws will scratch your camera mount)

Optional:

-Original Pentacon Six / Praktisix lens locking clamp  (3D-printable replacement included in STEP file)

Important Notes:

-Designed around the dimensional accuracy of printers like the Bambu Lab A1, more precise machines will work without modification to the original design

-Older or less accurate printers may require tolerance adjustments

-Do NOT change the overall height, except to compensate for EF bayonet thickness (final adapter length must remain 30.10 mm)

Print Settings (Tested):

-Printer: Bambu Lab A1

-Nozzle: 0.4 mm

-Layer height: 0.12 mm

-Walls: 4

-Top/Bottom layers: 10

-Infill: 85% (honeycomb)

-Material: PETG

(Yes, this is overbuilt. That is intentional.)

Material Recommendations:

-PETG – recommended

-ABS / ASA – acceptable if you understand shrinkage, your machines accuracy and calibration

-PLA – DO NOT USE

If you print this in PLA and something breaks, bends, or catastrophically fails, that’s on you and your life choices.

License / Usage -Do whatever you want with this model:

-modify it

-remix it

-improve it

-cause chaos responsibly

(Attribution appreciated but not required)

Stay creative and happy printing :)