Converting The Mentor Folding Reflex to 4x5
How to convert your Mentor Folding Reflex to accept modern 4x5 film holders.
As promised, here's a quick guide to converting your Mentor Folding Reflex to accept modern 4×5 film holders.
Fortunately, the film plane distance of modern 4×5 film holders matches that of the original Mentor holders, so there's no need to modify the depth at which the holder sits.
The conversion simply involves modifying the existing camera back to accommodate the larger holders, narrowing the film gate, and cutting a few grooves to match the shape of modern film holders.
Camera Compatibility
The camera I've converted is the 10×15 cm Mentor Folding Reflex, equipped with a 16.5 cm Tessar lens.
The smaller 9×12 cm model typically features a 15 cm Tessar lens. While the same general approach should work, the measurements provided below are specific to the 10×15 cm model and will differ for the smaller camera.
Modifications
The following measurements are in millimetres (mm) and correspond to the numbered modifications shown in the photographs.
Wooden replacement piece: Replace the original wooden piece with one measuring 200 × 18 × 7 mm.
Wooden replacement piece: Replace the second original wooden piece with one measuring 121 × 19 × 7 mm.
Film gate modification: Cut a slat to narrow the film gate, measuring 95 × 13 × 3.5 mm.
Film gate modification: Cut a second slat to narrow the film gate, measuring 95 × 12.5 × 3.5 mm.
Film holder groove: Cut a groove to accommodate the shape of the modern film holder, measuring 125 × 3.5 × 1.25 mm.
Film holder groove: Cut a second groove to match the film holder, measuring 125 × 13.5 × 1.25 mm.
Spring back fitting: Cut the rounded notches needed to accommodate the spring back. For my conversion, I used a spring back from a Burke & James 4×5 reducing back. Notch size and shape may vary depending on which spring back you use.
Final Thoughts
And that's it! It's a relatively straightforward conversion that allows this beautiful old camera to use readily available modern film holders without sacrificing its original character.
If you're considering doing this conversion yourself, feel free to reach out with any questions. I'm happy to help!
— Peter
