Ricoh 126c-flex camera mount to Sony E mount adapter

fixed f/2.8 aperture, might add an aperture ring in v5.

not sure if this adapter works with all lenses from this line (all lenses with the ricoh 126c-flex mount), only tested with the f=35mm 1:2.8 "RIKENON WIDE" lens (see https://www.facebook.com/groups/vintagelensclub/posts/1036535698272265/ )

i used the referenced/sourced Thing to get the E mount adapter, but everything else was modeled by me in blender. used a outer wall depth/thickness of 4mm.

i recommend 3d printing in a black filament, as the less light that's reflected on the inside of the adapter the less fogging you'll get. the E mount side might need some sanding or touching up to get it to fit in the camera body. i had to trim the under side of the flanges a bit with a sharpened chisel, but a knife, dremel, or sandpaper would work fine too. i also needed to add a ring of construction paper as a shim between the lens and adapter, as it's very slightly too short and the lens can focus beyond infinity without it. can be fixed by expanding the cylinder by about 0.1mm, but then you run the risk of needing to sand down that plane. slightly easier to add material in the form of shims than to remove it.

you can remix this to a different camera-side mount, but if you do just make sure to take the flange focal distance of your camera into account when adjusting this adapter. the distance between the sensor and the flat surface of the camera lens for this adapter is about 18mm (FFD for sony E mount) +43.3mm (approximate Z height of the adapter once mounted) == 61.3mm. though the last lens surface protrudes into the adapter a little bit so that number might be off.