Zeiss - Carl Zeiss Jena Jenazoom 70-210mm f/4.5-5.6 MC Macro consumer zoom, Canon FD variant
Carl Zeiss Jena sold this 70-210mm MC Macro zoom under the Jenazoom name late in the company's life, well after the era of the Jena primes that carry the reputation. It reached the UK market in a spread of SLR fittings rather than a single mount, and examples turn up today in Canon FD, Olympus OM, M42, Pentax K, Praktica B and Pentacon Six.
Published specifications for this zoom are hard to come by, and no elements-and-groups count, filter size or minimum focus figure is recorded here because none could be traced to a source worth quoting. Any confident spec sheet found elsewhere deserves care, as pages on this line frequently borrow numbers from other lenses.
It is widely taken to be a rebadged Japanese consumer zoom rather than a Jena optical design, though that has not been demonstrated. The practical point for a buyer is that the Zeiss name on the barrel does not carry the optical pedigree of a Flektogon or a Pancolar, and asking prices that assume otherwise are worth resisting.
A faster Jenazoom II 70-210mm f/2.8-4 exists and is a different lens, so check the aperture ring markings before buying. Work the zoom and focus barrels through full travel, look for haze between the groups against a bright light, and confirm the aperture blades snap cleanly and carry no oil.