Saturday, April 2, 2011

Using an M42 Focusing Helicoid on the NEX-5

Soulnibbler has asked how I used the M42 mount helicoid on the NEX without adding lots of space.  This may sound complicated but it's amazingly simple.  You just need the right c-mount to NEX adapter.  It's obvious why I choose the c-mount adapter as it's the thinest adapter available for NEX.  It only adds a few millimeters to the length of the helicoid.  Have a look at the picture below:

17-32mm Helicoid on left, C-Mount to NEX adapter on right. 

Note the two threads inside the C-Mount to NEX adapter.  The outer most thread has a 55mm thread while the middle thread size is 42mm.  You simply screw the helicoid onto the C-Mount to NEX adapter.  The one I used was bought from Rainbow Imaging.  They sell on eBay as well as Amazon and their own web site.  This one is very inexpensive for around $15 or less.  Click here to see a sample one they are selling.  I am not connected to them but I bought a few adapters from them and always get excellent service.  The best part, if you are in the USA or Canada, is that they ship from USA (at least when I bought from from eBay).

Perfect marriage -- Helicoid screwed onto the C-Mount adapter.  Very tight fit without lots of space.

Helicoid mounted on the NEX-5.

Helicoid with EL-Nikkor 50mm f2.8.

The helicoid I am using has a 52mm thread on the lens side, instead of the more common M42.  I have many odd lenses that have large rear mount and I find 52mm size is easy to find adapter for, since I have LOTs of useless filters I bought from the Outlet Store.  I just remove the glass and voila, useful adapter rings!  The last pictures shows the EL-Nikkor is mounted on the 52mm filter ring, and in turn, the filter ring is screwed on to the helicoid.  I do need to use electrical tape between the EL-Nikkor and 52mm filter ring, since they fit snuggly, but not very secure by themselves.

Hope you find this useful.


  1. nice lighting work too ... :-)

  2. Thanks obakesan. A single flash bounced from the ceiling. I used to light my stuff with multiple flash heads, but it's such a pain to setup and just couldn't be bothered with any more.

  3. yeah ... single flash mounted off camera and a single white card can do some great stuff.

  4. Interesting article. But I don't know if I completely understand all of it. Will it be possible to use other m42 lenses with this "2 in 1 adapter"? If it's possible to have shorter m42 adapters, why do they make them longer? Do you use this "adapter setup" for the SMC 50mm f1.4 as well?

  5. I have something to add to my previous comment I (anonymous) posted above.
    Have you checked out this lens: Schneider 80mm f4 Longar-Xenon-C Retina? Make a search for it on ebay.
    Do you know if it would be possible to fit it on the NEX-5? Because its size is amazing for being 80mm, and would be perfect for the NEX.

    I've been looking through your blog, and I must say I admire your passion for old lenses. I find all of your articles very interesting and inspirational.

  6. Anonymous/Niklas: the idea of a focusing helicoid is not really to be used with normal M42 mount lenses. It's to be used with lenses without focusing rings, like enlarging lenses, projection lenses, etc. There are dedicated and very cheap M42 to NEX adapters you can buy on eBay.

    As for the Schneider 80mm f4 lens, I have one myself, and it's indeed very sharp lens, but a bit slow with a maximum aperture of f4. You can also buy a DKL to NEX adapter to use this lens, though the adapter is pretty expensive, as adapters go.

  7. Ah, I see. I was looking at the helicoids on eBay, and they where pretty expensive as well(~$75 and up). But then, if I understand it correctly, the lens won't be completely fixed with the helicoid - meaning, the lens won't be perfecty aligned with the sensor. And as you mentioned in this artcile, not so secure (i.e. not very stable fix?). Or am I wrong?

    I recently bought my NEX-5, and I'm looking for manual lenses to use. I'm interested in something at the longer end, about 85-135mm. I would appreciate some recommendations from you. I've understood that you use a lot of projection. I would consider one for myself, but I don't want anything too complicated in terms of adapting it to the NEX and manual use.

    And after seeing some of your samples with the El-Nikkor 50mm, I would really consider it as well. The sharpness is amazing. I looked on eBay, but some of them had a wierd "flange plate" - do you know if it's removable? And there seem to be different models of this lens, but are they the same optically?

    I'm sorry for asking so many questions and making such a lengthy comment. But I hope you're okey with it :)

  8. I have a Rodagon 50mm 2.5 and the same helicoid as yours. Is it possible to adapt this to my G1 using a C-mount to m4/3s adapter and some epoxy. I'm not sure what the lens flange to sensor differences exist between the NEX and the M4/3s.

  9. @Paul: The m4/3 mount is 2mm longer than the NEX E-mount, but I don't see a problem getting your lens to focus to infinity. There is also a c-mount to M4/3 adapter that has the same M42 inner threads, as I have one of these. You really don't need to epoxy the mounts. Alternately, you can try the 49mm reversing ring for the M4/3. I order the 49mm, 52mm and 55mm reversing rings for the NEX, but due to Canada post worker strike, I have not received them yet. The advantage of the reversing rings are that they have a much bigger opening at the mount than the c-mount. I found that some lenses vignette due to the small opening, especially those longer lenses that don't sit closer to the sensor.

  10. Unfortunately that adapter is no longer available see below...

    Tks for ur inquiry.
    Sorry that the lens adapter is without M42 and 55 threads now.

    Sorry for inconvenience caused.

    - rainbowimaging

    1. Hi John, thanks for the update. It's really too bad that it's no longer available. I am sure other eBay sellers still have them. Sometimes the picture they used does not match what they ship, so it's good to ask first.