Konvas Lomo oct 18 to Canon EF mount Adapter

thingiverse

This is an adapter for ancient Konvas Cameras with Lomo, Lenkinap, KMZ Russian lenses and Oct 18 mounts for Canon EOS EF mounts. Konvas - Lomo Oct-18 lenses have a 57mm focal flange distance and 47mm diameter. (source: http://konvas.org/faq/faqs/faq/konvas-oct18-ost18-oct19-ost19-lens-mount-diagrams) With this adapter, you can focus at infinity if the lens physically fits your camera. If using an EOS reflex camera, check that the back focal distance (BFD) of the lens isn't too long or risk damaging your camera. Most Canon reflex cameras have 11mm space between the mount flange and inside body; any lens with a bigger BFD can damage your camera or prevent infinite focus. Using this adapter on a mirrorless camera with an extra adapter (Canon M, Sony E, Micro 4/3) allows you to use all Oct-18 lenses without worries. This version has three holes with insert M4 nuts for securing the lens with M4 nylon screws. A STL model without secure holes is also available; you can modify it as needed. The design isn't industrial standard but works well. When using prime lenses, note that you need to focus using the internal barrel because the external barrel is locked by this system. Be careful, as the inner barrel may completely come out of the lens if trying to focus too closely. The STL model is upside down; turn 180° in your slicer to use less support. Example photos were shot with a Lomo 135mm f/4.0 and 75mm f/2.3 lenses on an old APS-C Canon 400D without focus assist. Printer Settings: Printer: Tatara Steel A8 Rafts: Yes Supports: Yes Resolution: 0.1mm Infill: 66% Notes: The prototype seen in the picture was printed with a Anet A8, sliced using CraftWare. PLA 1.75 mm Temperature: 210° Layer height: 0.1mm Draw speed: 36mm/sec Shell loop count: 2 Top/Bottom Layer: 3 Infill density: 66% with Triangle grid ATTENTION: The STL model is upside down; turn 180° in your slicer to use less support. Post-Printing: Finishing: If your printer over-extrudes or isn't precise enough, you'll need to paper sand out some microns from the 47mm inside hole. Better safe than sorry. The side with EF mount doesn't require any finishing but lock and unlock a few times on a dummy EF female mount, then blow air through it to avoid dust entering your camera. If planning to use only Oct-18 lenses with EF mount cameras, you can force the lens into the adapter.