The teen Swiss Whiz a.k.a Oscar Oweson checks in with the JCH crew to give us an update on his latest mechanical concoction. Last year he wowed us with the Oxygen; what has he up his sleeve this time? Read on to find out more about the Panomicron Holmium.
The camera is called the Panomicron Holmium (67th element of the periodic table). Thought it would be a bit more fun and distinctive as a name than RF67.
The first thing I’d like to share with people about the camera is just the basic specs, it’s a 3D printed 6×7 ( 4:5 aspect i.e 56mmx70mm) rangefinder camera, it can use copal/ compur mounted lenses and focuses down to 0.91m. The camera has an optical viewfinder, 0.6x magnification, calculated for a 65mm lens.
I’ve only been working on it for around 4 months, in fact when I came and visited JCH HQ I had only been working on it for a week or two. I’m not sure on what’s more interesting for people so I’ll give you a broad overview and if you want me to elaborate on anything in particular then let me know.
The rangefinder mechanism is separate from the viewfinder and has a 1.5x magnifier in front of it to make if more precise. It’s built with optics you can source piece by piece online and attached to a CNC’d Aluminium base plate to make the base length as accurate as possible. It can accurately focus a 65m f/4 down to 0.91m right now, and should be able to focus a 80mm f/2.8 down to 0.91m if i could make the correct shaped cam for it. I can probably focus longer lenses accurately too, but I haven’t bothered with the calculations.
I’d love to share the principle of the rangefinder mechanism I’ve built and how it works, but I’m not sure how to without getting too technical. A fun fact is that the mirror inside the rangefinder only moves about 1.5 degrees from infinity to 1m, which is why it’s so complicated to make accurate rangefinders, you have to translate about 5mm of vertical travel to 1.5 degrees of rotation.
I’m particularly happy with the ratchet system i made for the advance, it’s a bit noisy but it eliminates the need for the two knobs like most home made medium format cameras have to keep the film tensioned. I’m still working on the counter system, as the two versions I’ve tried so far haven’t worked, since medium format film doesn’t have sprockets you have to rely simply on the friction between the film and the roller, which makes it a lot more complicated.
I also built and designed a 3d printed helicoid for the 65mm lens, it works fine and is accurate enough, but it would bind up when focused past infinity because of a design mistake, which made it slightly annoying to use, so I now use a chinese m65 helicoid instead.