DIY Contax N to NX lens adapter...

Because the FrankenKamera IV I'm building around a Toyo Robos 4x5 rear standard will be dedicated to my Contax N 17-35/f2.8 zoom and my Contax 645 primes and I also want to use it with my modified Samsung NX500 to take IR photos, as well as my A7R to taken visible light photos during the day and night, I thought it might be a good idea if I first tested the lenses and confirmed they perform well with IR light before I continue working on my larger project.

To that end, the quickest, easiest, least expensive way of doing this was to fabricate a lens mount adapter so I can mount all these lenses directly onto the NX500 body, which I have now done, as the photo below shows:

Basically, I used a Fotodiox Contax N-to-Fuji X lens adapter, removed its stupid aperture mechanism and all of its Fuji bits, then added the Samsung NX bits, made an aluminum spacer of the correct thickness to position everything in the appropriate places and -- voila!-- I now have what is very likely the world's only Contax N to Samsung NX lens adapter (dumb version, because it can't control the lenses electronic apertures)!

I mounted my Contax N 24-85 zoom on it (because I don't have an IR filter that will fit the 17-35's 95mm filter threads on hand) then took out with me on my morning walk with Miss Abby. Alas, the light wasn't very good due to the largely overcast sky, so I took only a few photos to see generally how well the lens performs with IR light.

Here's one of them:

I will need to do more testing, of course (and perhaps further fine-tune a bit the spacer thickness, because both the 17-35 and 24-85 zooms use two aspherical elements, which requires them to be very precisely aligned [i.e., within a few thousands of an inch] with the infinity marks on the lens in order to perform optimally.)

But my initial results from this morning display no evidence of any glaring issues (soft corners, hot spots, ghosting or flare, etc.), so I am encouraged.

Although the Contax N 24-85 zoom is much larger and heavier and has a slower max aperture than either the Contax 28/f2.8 prime of 35-70/f3.4 zoom lenses I've been using to do the majority of my IR photography so far, its slightly wider and longer focal lengths will be most welcome, as 28 mm is frequently a bit too long and 70 mm is frequently a bit too short.

And I am looking forward to testing the 17-35 zoom (for which I have ordered a 95mm to 82mm step-down ring, so I can use my 82mm Hoya R72 IR filter on it without any vignetting, he types while crossing his fingers!) sometime early next week, so stay tuned!