Triplet 2.8 to Sony NEX lens mount adapter

thingiverse

Sony NEX/E mount to Soviet Triplet 2.8/78 mount adapter. With this adapter you can use old Soviet projector lens (or similar size lens) on a Sony NEX/E-mount body. By rotating/moving the lens inside the adapter barrel and using manual focus aid on your camera screen you focus on the desired objects. The 1.5 mm hole on the mount body is for a small screw to guide the lens by helical groove. It is the easiest way as printing grooves inside the mount can be inaccurate whereas one screw holds the whole assembly perfectly. You may need to adjust the internal barrel diameter if your triplet has a diameter greater that 52.5 mm. Ideally, the lens should sit tight in the barrel but also allow for smooth rotational movement. The flange to flange distance of this adapter is approx. 26mm (25.4 mm technically). It allows infinity focus without any margin. You may need to tweak the Z scale up/down by 1% or so to make it work with your printer. With this package I include three model files: PRT for tweaking (if you need to change barrel dimensions), and STP and STL for printing. In PRT file you can adjust the barrel dimensions, just make sure the mount portion stays the same. IF it is downloaded as triplet_nex_26mm.1 rename it to triplet_nex_26mm.prt before opening in CAD editor.