Lensless M42 to Nikon Adapters

[Marcus Rowland]

I always wondered what use the lensless M42 to Nikon AI adapters are, since they won't focus to infinity and are usually advertised as macro. But I had one turn up in a job lot of lenses a few days ago, and finally tried it tonight, with a Helios 44-2 (58mm f2). The result was interesting.

The mount is made of fairly thin metal and only adds about 1mm to flange depth. M42 should be 45.46 mm, Nikon is 46.50 mm, with the adapter say 47.5 to 48.0, so the actual extension with the adapter is only about 2-2.5mm. As a result the Helios focused perfectly out to two meters or so, which means it would be a pretty good portrait lens. The same should apply to most other M42 lenses, they'll work fine within 2M or so (the exact distance obviously depends on the lens - some badly adjusted lenses may even focus to infinity). Given that these things are ridiculously cheap I'd strongly recommend buying one in case an M42 lens comes your way and you want to use it.

No photos because the weather is lousy and my flat is a total mess at present.

This is a similar adapter on eBay UK - £1 shipped from China - https://www.ebay.co.uk/itm/232517074055

I think they're all pretty much alike.

[Bjørn Rørslett]

Indeed useful, but be careful when mounting and unmounting as they easily become stuck or jam due to the overall thinness.

[Dr Klaus Schmitt]

Yep, I use(d) them since many years, works acceptably well

[Marcus Rowland]

I'll be honest, if I want to use an M42 lens I usually use my Canon body, since I've got a chipped adapter for that which doesn't need a compensating lens to focus to infinity, but it's nice to have the option to use one on the Nikon without the extra distortion.

[Josh Lewis]

I bought a Jupiter 11 in a lensless M42 adapter.

The lens is a rocket looking aluminum cylinder. The m42 threads are on the outside. There is no rear collar like I see on many pictures of the lens. The lens can keep screwing down into the adapter and just into F-Mount throat. There is nothing to stop it. You can screw it in deep enough to make up the flange distance and have infinity focus.

M42 is just smaller in diameter than the opening in the camera.