Generic L to M Close Focus Adapter Re-Greasing

I ordered this generic L to M adapter from Ali Express for about $50. It has exactly the same design as the 7Artisans and the Hoage, but the machining is somewhere between the 7Artisans and the Hoage.

As with the 7Artisans and the Hoage adapters the helicoid was quite stiff, so I opened it up to re-grease it with a lighter grease.

The disassembly is very easy and is a good introduction to working with a lens helicoids. The helicoid, like many lens helicoids, is actually two helicoids which translate the rotation of the black knurled ring to a back and forth motion of the lens.

It’s important that the adapter be machined to maintain infinity focus. When the lens is focussed at infinity the adapter should all the whole assembly to focus at infinity – if it’s too long or too short, you either won’t be able to reach infinity, or will focus past it. Focusing past infinity at least allows you to get to infinity, but ideally it will allow you to reach infinity without going past.

This specific example did focus slightly past infinity but it’s good enough that I didn’t bother modifying it.

This is the L mounting plate that screws in the L-mount camera.

This is the M mounting plate that accepts the M mount lens (or an LTM lens adapted to M mount).

Start by removing the 4 screws on the M mount side.

Lift out the M lens mount plate, then remove the release button and the companion spring.

Remove the two small screws securing the brass helicoid coupling pin.

Unscrew the L mount plate from the helicoid, as always making a note of where the pieces separate so you can re-assemble it. The helicoids are simple enough that you could probably get it back together with trial and error, but it’s better to make things.

Disassemble the inner helicoid, again noting where they come apart.

Clean all the pieces. I use a microfiber cleaning cloth followed by 99.9% alcohol and a small paint brush. It looks like they lubricated this thing with petroleum jelly.

Re-grease the helicoid. I think Helimax XP works well and give s medium amount of resistance.

Use just enough grease for the helicoids to move smoothly. I use a small hobby paint brush to apply the grease. Work it back and forth a few times and wipe up any excess.