Mods, DIY & Lens Adapting

A Little Bricolage, or: How I Recovered Two Old Lenses – By Jordi Fradera

May 7, 2020

I’ll start with the Canon Super-Canomatic R 135mm f/2.5, but before I get going, its relevant to say that both Canon, Pentax K and Sony A have the same distance between lens mount and film/sensor, this made both these jobs easier. In 1959 I bought a Canon Canonflex camera with a 50mm lens. (yellow coated), shortly after I bought the 135mm telephoto lens. I used the equipment for years until it was stored in a closet. Later some thieves entered my house and took the camera but the 135 mm was saved. I still remember the enormous weight of the camera and its wonderful features.

Around 1978, with a Pentax ME and various lenses already in my possession, I adapted the Canomatic R135mm. to the Pentax camera through a turned part (not by me) and a Pentax K / 42 mm adapter. It worked perfectly but ended up in a closet again.

In 2017 I recovered the 135mm. And I decided to adapt it to my new Sony A37 – a camera that’s almost as small as the old Pentax ME. I quickly made the adaptation by swapping the Pentax K 42mm adapter for a Sony A 42mm adapter.

Of course the automatic diaphragm of the Canomatic R disappeared, I eliminated several parts, blocked the two diaphragm control rings in one and even had to disassemble optics and iris to free them up since they had become gummed up with oil over time. It was quite a puzzle! Now, as a manual lens it is operational but it does not focus to infinity and it is equivalent to a 200mm on the APS format camera. I could solve the issue of infinity focus, but I haven’t tried hard enough yet.

f/2.5 1/40 -0.7

f/16 1/100 does not focus infinity

f/8 1/500

Pentax M 28mm F2.8

I bought the aforementioned Pentax ME camera in 1976. I have fond memories of it too, it was small and handy, with a wonderful viewfinder. I bought the 28mm and a 200mm. Several years later the foam gaskets near the mirror degraded and dirtied the entire interior of the camera. I tried to repair it, but ended up doing more harm than good, leaving it useless and completely disassembled. I still have the remains in a display case.

In 2017 I decided to recover the 28mm and use it for my Sony A37. I did the DIY work at home. I disassembled, cut, filed, drilled etc. until I could mount a Sony A adapter to it. I used an M42 adapter which I machined to remove the 42mm thread. A bit of Araldite and voila, it was operational. It works without the diaphragm automation, it focuses up to infinity and can be used without problems on the Sony A37. As an APS format camera the lens provides an equivalent to 42mm.

f8 1/500

f/5.6 1/8 with tripod and timer

f/4 1/4 with tripod and timer


As you’ve read, these two lenses had sat unused for many years without any practical use to me. Modifying them presented me with a bit of a fun challenge and something to do whilst I’ve been keeping myself incarcerated away from the virus. I’m pleased with the results, and now look forward to a time when I can use them to take photos of more than I’ve been able to so far.

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  • Reply
    Ron Peters
    May 7, 2020 at 3:09 pm

    Canon EF: 44mm, Sony A: 44.5mm, Pentax K: 45.46mm.

    • Reply
      Jordi Fradera
      May 7, 2020 at 6:38 pm

      I completely agree.
      For the 28mm Pentax I used a Sony A / M42x1 adapter, the Pentax K and M42 distances are the same: 45.46mm. and it worked fine.
      For the Canon it had long ago made an adaptation for Pentax K and by using the Sony A / M42 adapter without making any further modifications it was too far apart. I already realized it and I said it in the post but I didn’t make the effort to repair it.
      Thank you

  • Reply
    Roger B.
    May 17, 2020 at 11:43 pm

    Fans of bargain PK wides: Look for the 28mm f3.5 SMC-M. Smaller, usually less costly than the f2.8, and held in great esteem by we Pentax nut jobs.

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