MRF: a LiDAR-powered, lens-coupled medium format film rangefiner for Mamiya Press Lenses

The (M)edium format (R)ange(F)inder is a 3D-printable camera that uses relatively easy to source, off-the-shelf components. 

See the Github repo for the most up to date files, including firmware and KiCAD / Gerber files for the custom PCB.

Update 4 Jun 2024:

I have updated the wall thickness of the lens cone and rear film door, as they were not 100% light tight as they were when printed with the MJF process in dyed-black Nylon 12. If you printed the previous version with an FDM machine with the recommended wall count and infill there is no need to re-print. 

Further updates: 

• More support added to the LiDAR mount
• An extra channel for wiring added to the bottom of the viewfinder to make it easier to avoid pinching

Update 1 Jun 2024:

Instead of using a simple power switch to pull the EN/PWR pin to GND, it turns out for maximum battery life, you need to disconnect the STEMMA QT power line as well. To that end I've updated the build guide with details, and added new parts:

• Button mount - to mound the new buttton to the bottom plate
• Button - a round button top that snaps onto the square button peg

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This is my ideal medium format film camera.

 Some of the highlights:

• Use any of the Mamiya Universal Press lenses and calibrate them in-camera
• Shoot 35mm Panoramas, 6x4.5, 6x6 and 6x7 all in the same camera by simply selecting the relevant format from the in-camera configuration menu and installing the relevant mask
• Accurate frame counting for each format
• Upgraded "LiDAR" with higher accuracy and distance up to 12m
• In-viewfinder display with
  • Light-meter with aperture range set by selected lens
  • Lens focus distance display, and LiDAR rangefinder distance display
  • Focus accuracy indicator
  • Dynamic frame lines with size determined by lens selection, and masking determined by select format
  • Horizon level indicator
• External display with frame count, battery life, selected format, and selected lens

The bill of materials and everything you need to know is in the build guide.

Here's a short walkthrough of the camera in on Instagram.

You can see a few examples of photos taken with various prototypes on Instagram as well:

• https://www.instagram.com/p/C43rso2oybJ
• https://www.instagram.com/p/C6Ep1m4oHzi
• https://www.instagram.com/p/C6nwu8qoQKy
• https://www.instagram.com/p/C6zQlxAIzB3
• https://www.instagram.com/p/C7MERYwoWzO/

• I changed it from 6x9 to 6x7 to make room for a channel for the wires for the electronics and added a holder for the position sensor that couples to the lens
• Created a custom Mamiya Universal Press lens mount
• Removed the frame counting mechanism and added more teeth and tighter tolerances to the ratchet mechanism, replacing the wind-on lever with a knob, and coupling the whole thing to a rotary encoder to count frames electronically
• Made a custom top plate to house the viewfinder, optics and electronics
• Added a magnetic frame masking system to enable you to shoot multiple formats with the same camera
• Designed a custom bottom plate to house the electronics and battery
• Many other small tweaks to allow for the complexity of this camera to be realised