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.

Few More Pictures from the DIY Soft Focus Lens

[updated Dec-30-2009 for spelling errors]

Tried out the lens more yesterday. Found that the aperture helps very little. Stopping way down produced severe vignetting, but does not seem to affect Depth of Field much. Focusing is tough because everything looks soft and it's hard to find a focus point. The soft effect tend to be too much. Placing the lens element exposed in the front of the lens probably causes that. As expected, back lit scenes are mostly unusable. Some fine tuning/redesign is in order.

Regardless, it was a fun exercise. My next project is to create my own Lens Baby :-)

All pictures taken with a Canon 5D and my DIY soft focus Lens. Click on the picture to see a larger version.