M42 Lens To Leica M Body (Techart Pro LM-EA7) Adapter

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M42 is widely regarded as a universal screw thread mount for Single Lens Reflex cameras, closely associated with Praktica and Pentax brands. However, it was actually utilized by numerous other manufacturers, including Fujica, Mamiya/Sekor, and Zenit. Due to its open standard and relatively long flange distance, M42 has become a popular choice for adapting lenses to various mounts, excluding Nikon F. Many commercial adapters are available for converting M42 lenses to other mounts, such as Leica M. The question remains: why 3D print this particular adapter? A simple answer might be "because we can," but this is an easy print in one piece, including the M42 screw thread. There are two compelling reasons to do so. Firstly, an M42 to M adapter enables the latest Sony E mount bodies to autofocus these manual lenses via the Techart Pro LM-EA7 adapter, which has a 700g weight drive limit, making it essential to minimize adapter weight. Secondly, later Mamiya/Sekor M42 lenses have the aperture ring extending around the mount flange, but commercial adapters often feature overly wide flanges that prevent these lenses from mounting properly. There are also potential issues with some M42 adapters being too thick on the M side to fit onto the LM-EA7. In any case, this adapter avoids all these problems. The last two shots were taken using the LM-EA7 autofocus with a manual Mamiya/Sekor 55mm f/1.8 lens. Note that you can adjust the autofocus range by not leaving the manual focus ring set to infinity. Print Settings: Printer Brand: MakerGear Printer: M2 Rafts: No Supports: No Resolution: 0.25mm Infill: 25% Notes: A straightforward print. I used dishwasher-safe high-temp black PLA. It should be a little tight, so work a lens into the mount before attaching it to a camera – this way, you can clean any small shards that the flange might cut when fitting a lens for the first time. The M42 thread prints directly and shouldn't require post-processing. A detail worth noting is that many adapters don't have the thread stop the lens at the correct rotational position... this one should – at least it does with the lenses I've tested. Post-Printing: Usage Notes: Be a little careful when threading a lens onto the adapter, as the metal thread on the lens can damage the printed thread if you cross-thread it. This adapter does not have a ledge to depress the stop-down pin found in the back of most M42 lenses. Therefore, the lens must be set to operate in Manual aperture mode, not Automatic. See http://www.instructables.com/id/M42-Lens-Aperture-Control-on-Modern-DSLRs/ for details.