Ensign Anastigmat Series VI, No. 0, f5.6 (Summer 2017)

This lens came to me already liberated from an old Ensign folding camera (not sure of the model, unfortunately). My pre-purchase research suggested that it was a rebadged Beck Isostigmar – an interesting design. I knew that the Isostigmar was also offered as an Ensign Anastigmat, and the beauty ring markings – series, f-stop, etc. – matched the information I was able to find online.

(No focal length is indicated; the field of view seems to suggest something in the neighborhood of 200mm.)

When I opened the lens for cleaning, however, I discovered that the optical scheme was different. My lens has four elements rather than the Isostigmar's five; it doesn't seem to conform fully to any established type, but one could classify it, I suppose, as some kind of variant Unar, with the stop placed between the third and fourth elements rather than between the second and third.

It's certainly not a searingly sharp lens, especially at pixel-peeping magnification. But stopped down one click, it's agreeably crisp, with attractive out-of-focus rendering. Plasticity is excellent, and color is lovely and subtle. It benefits, unsurprisingly, from a discreet boost in contrast – as do most uncoated lenses with this number of air-glass interfaces. A deep hood is also a must.

The Isostigmar is an intriguing lens, and I had looked forward to giving it a trial. But this one is fascinating in its own right – partly, I admit, because it appears to defy easy categorization.

Note that there's a bit of vignetting evident in some of these images. It's probably attributable to the lens-mounting arrangement: helicoid tube plus several extension tubes.