In 2013, on a whim, I bought a secondhand Carl Zeiss Jena 50mm Tessar lens in M42 mount. This is unquestionably the cheapest way of acquiring a Carl Zeiss lens but keep in mind the ‘Jena’ part of the designation, indicating that it was made in East Germany (DDR) prior to German reunification. East German cameras and lenses were good value but not at the cutting edge of technological development. My Tessar cost £12. It was a real bargain.

Dealers used to offer these as a cheaper alternative to a faster lens when buying a new screw-thread camera during the 1970s. The maximum aperture of the 50mm Tessar is only f/2.8. It is all metal and glass and nice to handle and use. Pictures are sharp, as you would expect from a tried and tested Tessar design. Later, when I acquired more old M42 screw-thread lenses, I found I preferred the CZJ Tessar to the more expensive Pentacon 50mm f/1.8 which came with a Praktica MTL5 camera as an eBay sale. The Tessar was nicer to handle and provided better results. It focussed closer too. Only its light-gathering capability was worse. The Pentacon 50mm f/1.8 is the last version of the Meyer-Optik "Oreston" 50mm f/1.8 and is also of East German origin. It ought to be at least as good as the Tessar. Maybe my sample escaped quality control.

The problem I had with the Tessar was that it wouldn’t fit a Nikon, at least not without an adapter, and it turned out that the Nikon mount wasn’t the most suitable for M42 lenses anyway. Canon EOS and Pentax were the better options in that regard. So after a bit of freelensing with my new Tessar and an old Nikon D50 (a technique whereby you simply hold the lens tight against the camera and hope for the best) I bought a Canon EOS 20D on eBay. With a cheap M42 - EOS adapter I was in business.

Using that combination was a bit challenging, but good fun and quite instructive. Only metered manual and aperture-priority modes are available and there is no communication between lens and camera. Later I discovered adapters with contacts which fool the camera into indicating focus confirmation. They don’t cost much more and are worth the extra, provided they don’t fry the camera’s electronics which has apparently been known.

Later I sold the Canon EOS 20D at only a slight loss and considered my excursion into screw-thread lenses finished. But after a short intermission the M42 compulsion returned. I bought an EOS 30D and amongst other bargains a Tomioka-made Chinon 55mm f/1.4 lens attached to a Chinon CX from circa 1976. These are highly prized by the cognoscenti and I prefer mine to even the Helios-44 which I also acquired.

The EOS 30D is only a warmed-over revision of the 20D but it has a bigger screen on the back which is useful. Its digital menu is the simplest I have found in my limited experience; it is apparently almost identical to the original EOS 5D of similar vintage. I tried a Canon EOS 40D but despite ‘live view’ and more megapixels, I disliked it chiefly because of its Byzantine menu. In my opinion Canon ought to have retained the glorious ease of use of the 30D.

All of these old digital cameras come at a fraction of their original cost and are often sold simply because of upgrade mania. Unless you are unlucky, you can try them and use them short-term before selling for around the price you paid; sometimes a bit less - regard the difference as your rental cost - occasionally a bit more, giving cause for celebration. However, the undiminished joy of using the EOS 30D, especially when teamed with the Canon EF 35-105mm f/3.5-4.5 lens (1987 - 94 and impressively usable at all focal lengths and apertures) or the Chinon 55mm f/1.4, has made it a long-term feature and I may never recover the £59.78 I shelled out four years ago.

I think a slight photographic diversion as described above can invigorate your work, generate some unexpected and happy results, and extend your knowledge of making a camera work. Old lenses in particular can reveal a smattering of the kind of character we used to have in the days of widespread film use but which is now mostly designed out in the manufacturers’ quest for consistency and perfection.