Tutorials & Guides

How I Loaded and Shot a Univex Mercury with 35mm Kodak Ektar 100 – by Stuart Jenkins

July 15, 2021

Universal Camera Corporation launched their Univex Mercury CC model in 1938, along with their proprietary #200 series films. It’s basically 35mm film, but on an open roll. The manual shows it having paper backing on the ends only, a bit like 220 film, to protect it from light while loading. Trouble is, the backing paper is perforated, which rather defeats the object.

The camera is often described as ‘half frame’ but that’s not strictly true. The image size is 25x19mm in portrait format, so it will just touch the perforations on both sides of 35mm film. Each frame winds the film on by 4.5 perforations, more than half of the 8 perforations for a full 35mm frame. The frame counter goes up to 36.

Can I use my camera?

I restored my Mercury a couple of years ago and finished it with some nice dark green leatherette. Since then I’ve been itching to use it. 35mm film will physically fit, if you can find a way to get it into and out of the camera without exposing it. The theory sounds simple. Inside a changing bag, just attach a length of 35mm film to both of the spools, roll it up onto the feed spool, and put it into the camera. I practiced on some old exposed film and found that there’s an awful lot that can go wrong. I could feel an engineering project coming on.

First, make a new spool

New 3D-printed spool on the left, original spool on the right

You need to have at least one original spool, because it has a special drive gear on the bottom. The gear isn’t fixed, but uses a spring washer that acts as a clutch and allows it to slip a little. That way the takeup spool can be driven a little faster than the film is coming off the sprocket, which keeps it tightly wound.  On the feed side, the spool engages with a little gear in the film chamber that drives a film transport indicator on the bottom plate. My camera only came with one spool, but as there’s no need for a slipping clutch on the feed side I was able to 3D print another one with a fixed gear on the bottom.

The blue spring-steel washer allows the drive gear to slip, but it’s quite stiff

Spool loading machine

I used FreeCAD software to design a shape that would hold a 35mm cassette at one end, hold the Univex feed spool at the other, and enable the spool to be turned by a known number of revolutions. A steel arm is just springy enough to hold the spool against the drive knob.

The 3D-printed shape

This enables a good alignment from the cassette to the spool, so the film will go on straight. Once inside the changing bag, I pulled some film out of the cassette, cut it straight across, and used tape to attach it to the 3D-printed spool (which has no slots). Pinching the perforations on one edge of the film as it moves will maintain the tension and make sure the roll is tight.

Film winding onto the spool

Previous experimentation in daylight with an exposed film showed that half of a 135-36 roll is 17 turns of the winding knob. Once wound, I kept the film in place on the spool using a clip made out of 15mm plastic plumbing pipe. That meant I could cut the film without it all unravelling. It turned out to be enough for 27 exposures.

Cutting to length, with the clip in place

Now I need some daylight

I knew that attaching the cut end to the original spool inside a changing bag was going to be difficult. It has to be cut on each side to leave a central tongue 22mm wide. The tongue then needs to be threaded onto the spool, and a bit of tape to finish wouldn’t hurt. Tricky to do accurately.  My solution was to find a way of doing that bit outside the changing bag. I 3D-printed a box with a sealed lid to put the loaded spool into.  Then then it can be brought out into the light.

3D-printed box with a foam seal

The free end sticks out through the foam seal

Now I could cut the film to shape and attach it to the spool without any stress, because I could see what I was doing. The only difficult bit is to remember to attach it the right way round.

Elastic bands hold the lid in place

Back into the changing bag

The box and the camera go into the changing bag. The box can be opened and the takeup spool put into the camera. The clip is removed from the feed spool and it is carefully placed into the feed side while keeping the film taut across the film plane.

The film in the camera. A good fit.

Once the feed spool is in place, it needs just enough friction to stop it unravelling. Originally there was a thin sprung steel arm for that purpose, but it’s not a good solution. I added some thick open foam to provide just the right amount of drag.

Foam friction pads in the feed chamber

Using the camera

For its first outing in decades, I treated it to half a roll of Extar 100 and took a trip to the seaside at Cromer, then finished off the roll on an evening photowalk in Norwich. It’s a delight to use, and the mellow ‘schhhhhhhhhhhluk’ sound of the shutter is totally unique. The only downside of that is shutter lag, between the start of the shutter disc’s motion and the image being captured. Despite the top shutter speed of 1/1000s, it’s a factor to remember if you want to try panning action shots. The tiny viewfinder discourages that sort of use anyway.

Take note of the spinning film transport indicator on the base when you’re winding on. As you’re getting towards the end of the film, start watching it like a hawk. When it stops spinning, you’re done and any more shots will just be multiple exposures.

The shots

Tractor on Cromer beach. Aperture f16.

Sea view at Cromer. Aperture f11.

Seaside seaweed. Aperture f5.6

The old Laurence Scott & Electromotors factory in Norwich

River frontage of the old Colman’s mustard factory in Norwich

What next?

The Mercury has interchangeable lenses, but no other focal lengths were available. The early Tricor 35mm f3.5 was superseded by an f2.7 version and a Hexar 35mm f2.0. The focus helicoid is behind the mount (which has an imperial 15/16″-32 UNF thread) so the lens itself doesn’t need a focusing mechanism. I might try to find a decent half-frame 28mm that I can adapt to fit. An accessory shoe for a bigger auxiliary viewfinder is conveniently placed above the standard one.

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26 Comments

  • Reply
    Paul Brant
    July 15, 2021 at 10:13 am

    I’d thought it impossible to use these nowadays.
    Great interesting post with some good shots .
    Many thanks.

    • Reply
      Stuart Jenkins
      July 15, 2021 at 11:16 am

      Thanks Paul!

  • Reply
    Tom Perry
    July 15, 2021 at 10:24 am

    Appreciate the insane level of effort to get this beautiful camera usable again. Bravo!

    • Reply
      Stuart Jenkins
      July 15, 2021 at 11:17 am

      Thanks Tom!

  • Reply
    David Campbell
    July 15, 2021 at 11:28 am

    Great article! I have one of these that I bought about a year ago. It will need some work to restore to usability. The shutter mechanism is probably gummed up a bit and stuck around 1/30th or 1/15th of a second. Before I bought it I had never heard of this camera. Also interesting that it is machined out of solid aluminum and the rotating shutter is akin to those used on movie cameras. I’m not up to your level of problem-solving skills in manufacturing a film loading adapter, so I will have to see what I might be able to do if I ever get to the point of actually trying to run a roll of film through this little beastie!

    • Reply
      Stuart Jenkins
      July 15, 2021 at 11:39 am

      Thanks David! I used Rick Oleson’s repair notes on the Mercury II (on his website) to disassemble the camera. It really only needed the shutter mechanism to be flushed out with lighter fluid. When I reassembled it, I deliberately left out the four coil springs that push the focusing mechanism away from the film plane, presumably to eliminate backlash. They’re not necessary, and they’re too strong so they just made the focusing really stiff. Instead I just used good quality dampening grease on the helicoid and it feels much better.

      • Reply
        David Campbell
        July 18, 2021 at 8:40 pm

        Next time I haul it out I will try the lighter fluid on it. Thanks. I will take a look at Rick Oleson’s website and see what he has to say about this camera. I’m in the U.S., by the way. I guess most of your readers are in the U.K.?

        • Reply
          Stuart Jenkins
          July 18, 2021 at 11:02 pm

          Site owner Hamish is also in the UK but it seems to be a pretty international readership.

  • Reply
    Calum Davey
    July 15, 2021 at 11:42 am

    Was starting to think ‘gosh this is taking a lot of effort’ and then saw the results and could imagine the immense satisfaction of resurrecting such an interesting camera. Lovely shots — I think I prefer the aspect ratio to 35mm! Truly an amazing article, thanks Tom

    • Reply
      Stuart Jenkins
      July 15, 2021 at 11:45 am

      Thank you Calum!

  • Reply
    Kurt Ingham
    July 15, 2021 at 2:38 pm

    Superb!-
    Is there a possibility I could purchase copies of the spool and loading device from you? I have no 3D printing capability myself
    Thank you
    Kurt Ingham

    • Reply
      Stuart Jenkins
      July 15, 2021 at 2:46 pm

      Hi Kurt, thank you! I can see your email address in the back-end of the system. I’ll drop you an email later and we’ll see what we can work out.

    • Reply
      Peggy
      July 17, 2021 at 11:51 am

      That is amazing, well done. I am so impressed with all the 3D printing to solve problems. And the final images, double wow, so sharp.

      • Reply
        Stuart Jenkins
        July 17, 2021 at 12:39 pm

        Thank you Peggy!

  • Reply
    CP93
    July 15, 2021 at 3:02 pm

    Very nice. I just bought a second model, which uses regular 35mm, at a local antique shop for $40. Currently testing it with some CineStill BWXX. I know that at the fastest shutter speeds the shutter sometimes doesn’t close, so we’ll see what comes out. Next to find someone to process half-frame B&W 35mm.

    • Reply
      Stuart Jenkins
      July 15, 2021 at 3:05 pm

      Thanks! You could always have a go at processing it yourself. No darkroom needed, just a changing bag.

  • Reply
    Philip Lambert
    July 15, 2021 at 4:09 pm

    Amazingly talented work.
    There are often cheap half frame cameras on eBay .
    I bought an Olympus EES for £30 that works perfectly and another for£12 that seems to (untried). I have an old Minox 35mm somewhere that stopped working, optically very good. Back focus dimension unknown.
    My Olympus gives sharp results on low-speed colour negative rated at half box speed. Maybe you could find a non-working example.
    Phil

    • Reply
      Stuart Jenkins
      July 15, 2021 at 4:17 pm

      Thank you Philip. Yes, they might be possible options. I might need something that has a manual aperture ring at the front of the lens though. I’ll keep looking.

  • Reply
    Eric Risse
    July 15, 2021 at 7:42 pm

    There were other focal length lenses, but they re quite rare! I’ve only seen a photo of one.

    • Reply
      Stuart Jenkins
      July 16, 2021 at 5:12 am

      I stand corrected Eric – what other focal lengths have you seen?

  • Reply
    Louis A. Sousa
    July 16, 2021 at 2:38 am

    Wow, perseverance paid off in spades. Well done.

    • Reply
      Stuart Jenkins
      July 16, 2021 at 5:13 am

      Thank you Louis!

  • Reply
    Scott Gitlin
    July 16, 2021 at 3:13 am

    What a great story! if that camera could talk it would say, “Thank you!” And it did deliver fine results.

    • Reply
      Stuart Jenkins
      July 16, 2021 at 5:14 am

      Thank you Scott!

  • Reply
    Brian Nicholls
    July 16, 2021 at 8:32 am

    Amazing article and results Stuart! I don’t have your patience and resolve for all the fiddly modifications, but I would definitely buy one of these just to continually stare at its aesthetic beauty.

    • Reply
      Stuart Jenkins
      July 16, 2021 at 8:37 am

      Thank you Brian!

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