EF/EF-S to EF-M macro adapter

prusaprinters

<p>Adapter to use Canon EF/EF-S mount lenses with EF-M cameras. Doubles as an adjustable extension tube with 0-10mm extension range, perfect for extreme close-ups with ultra wide-angle lenses.</p> <p>Why not use a regular EF/EF-M adapter with a short extension tube? While a short extension tube works for most lenses, using the shortest available extension tube with a lens with a very short focal length will bring the maximum focusing distance <em>inside</em> the lens. Sometimes you want to bring your minimum focusing distance in just a little bit, and the ideal extension tube would be 3mm. Except the bayonet attachment on an EF lens mount is ~5.5mm long, so it is physically impossible to make an extension tube shorter than ~6mm. The only way to extend the lens mount is by adapting to a different lens mount that has a shorter flange distance, hence an EF to EF-M macro adapter.</p> <h3>Print instructions</h3><p>Print each piece separately and check the fit of the bayonet parts with your camera/lens. You may need to slightly tweak the XY scaling to get the pieces to fit nicely. My parts fit well with 0.1mm layer height.</p> <p>I added 0.2mm extra clearance on the internal to get the threads to work off my printer. If your threads don't want to turn a little bit of sanding should get them to mate properly. If the threads are too sloppy you can reduce the clearance in the .f3d file or slightly increase the XY scaling of the EM-M thread part.</p> <p>Once you are satisfied with the fit of the bayonet and thread parts, glue the bayonets to their respective threads. I used regular CA/super glue with PLA parts. <em>WARNING</em> If you use super glue let the glue dry for several hours before attempting to use the adapter. Super glue has a tendency to off-gas well after it initially appears to be dry and can permanently damage your camera if you get super glue residue on the sensor.</p> <p>The EF-M side of the adapter should slot into your camera and the locking pin should properly click into place. Your lens should screw snugly into the EF side of the adapter, although you may need to force it a little the first time depending on how sharp the layer heights were on your EF bayonet print.</p> <p><em>OTHER WARNING</em> I have not had issues with dust on my camera sensor when using this adapter, but a commenter on Hackaday pointed out that the bigger danger is dust in the shutter mechanism or focus motor, which you won't know about until your camera/lens breaks. I use this adapter to attach a cheap lens to a cheap camera that is meant to be abused. If you are concerned for your EOS M50 and 24-70mm F/2.8 L or whatever, stick to stuff that you can find on B&amp;H.</p> <p>Issues/Improvements:<br/> -- Red/White dots for aligning the lens/adapter/camera when attaching would be nice. Would require adding some sort of rotational alignment feature to the EF thread/bayonet parts.</p> <p>-- The EF-M side of the adapter is a little awkward to attach/detach. The simplest solution would be to increase the thickness of the ring that mates to the flange surface by a couple mm so it is easier to grip, but that would mess with the effective extension tube range. The EF side of the adapter could be shortened to maintain 0mm extension and infinity focus (0-8mm extension) or left as-is and lose infinity focus (2-10mm extension).</p> <p>-- Electrical connection between the camera and lens would be nice for AF/aperture control, but would be extremely difficult to implement with a rotating adjustment... Perhaps I will try to make a dust pump version of this adapter in the future.</p> <p>-- This technique can be used with other lens mounts, as long as there is enough difference between the native flange distances of the different mounts. Canon EF to Canon RF or Sony E mounts would be great candidates. If you make your own, please upload a remix!</p>