Latest Meyer Optik Trioplan conversion.

Everyone knows that Trioplans cost an arm and a leg. Most of them come in Exakta mounts and they can't readily be converted to something we Pentaxians (or any otherians) can use. Enter the standard 'between the wars' bellows camera! A lot of them look like they've been in the wars and, like the one in question here, have been badly stored and knocked about.

These cameras consist of three distinct parts:
A light tight metal or wooden box with provision for either glass plates, sheet film or roll film transport.
A shutter to control the light admitted into the metal box with aperture and exposure controls.
And a lens in front of the shutter. Most of these enable the front element to be screwed outwards or inwards in order to focus.

Now throw everything away except for the shutter and the lens. I described a while back how this whole unit can be fitted with an M42 thread. That is then attached (by trial and error) to the right length of extension tube to enable infinity focus with the shortest extension possible. You can then make final focus by screwing the front element in and out, as originally intended.

Now swap one of the extension pieces with a focusing helicoid. The original designers never envisioned this trick! It enables you to screw the front element all (or part) the way out, as if it were a modestly magnifying macro lens which will bring very close subjects into focus at (say) two or three feet with a 105mm lens. The helicoid is used to refine that focus while the background doesn't have a hope of being anywhere near focus. The result is mega bubble bokeh if there are sufficient bright objects in the background to produce the out of focus bubbles. What you are actually doing by screwing the front element in and out is changing the focal length of the entire assembly! That is then focused by using the helicoid.

The 'bubbles' are produced due to the near circular aperture of a multi-bladed Meyer Optik iris. Fully open you get big bubbles which reduce in size as you stop down until you reach a point where the image appears more 'conventional'. In short, you can use one of these converted lens-shutter-helicoid assemblies over the entire range from high quality conventional photography to near macro with or without 'Trioplan bubbles', as you choose.

I finally got this one calibrated with its extension tubes this afternoon and I took it into the garden on the end of a K1. This image is the very first shot I took with it. The withered purple toadflax in the foreground is about 3 feet away. The front element has been screwed right out to achieve this. The background is a mixture of green leaves and the autumn colours of an acer tree caught in the sunshine. Had there not been a focusing helicoid I would have had to use the front element alone to focus which would have meant me stepping back about 6 to 8 feet and so bringing both foreground and background together, thus producing a 'nice' conventional shot,

I hope that lot makes sense - here is the result ....

Very interesting David, I had no idea about most of it, but thanks for sharing.
Nice picture too. It would be nice to see a picture of this lens attached to the k1 of course

Indeed, a picture says a thousand words.

At the expense of them being taken by a Samsung mobile phone while sitting before the PentaxUser website ....










This link will provide a year of manufacture calculator for many vintage lenses based on their serial number.
It says mine was made in 1934.

Looks impressive too! thanks.

David Thanks for the link to the year of manufacture site. Checking my Schneider Kreuznach Radionar it gives a date of 1951 which ties in with the Franka Rolfix camera I got the lens from. The camera is marked Made in Germany US Zone so just after the Second World War.

Radionars are truly superb lenses. Consequently, you don't see many of them since folk won't part with them (I have two). Do put it on a camera and post some pictures from it please.