MicrobeHunter.com Microscopy Forum

Finally got one of these micro-Tessar lenses on the cheap so I wanted to figure out what was the deal. I tell you, not the best all-purpose lens. It's popular in photography as a low-cost, decent lens and I can see some advantage in depth-of-focus and planarity over the old achromat, but at the sacrifice of a ton of light and resolution. Here is the 16mm Tessar first, followed by the contemporaneous B&L 10x achromat, subject is plumularia




Another thing I can think of is that the Tessar produces a much wider image also, maybe even constrained by this microscope's drawtube but certainly larger than the achromat. I think this must be the real application.

The Tessar was a major Zeiss photo lens design, an improvement on the Anastigmat. Early 20th century . Back before the first W.W. , Zeiss, B & L and Saegmuller( gunsights) formed what was called the Triple Alliance. B & L was licensed to sell various Zeiss optics in N.A. : Zeiss therefore avoiding tariffs. Zeiss withdrew in 1915 because B & L was selling binoculars based on Zeiss patents to the Brits.
During the period of the alliance B & L manufactured Tessars under license and probably some time after the war tol. There were many virtually identical designs. Kodak Ektar, Schneider Xenar.
B & L used the little ones as microscope photo lenses. Does yours not have F stops on it? I have seen some that do but I can't be sure they were B & L.

No f stops, just the equivalent focus. It also has a little more working distance than the achromat.

I have seen a Tessar condenser as well, and maybe it would help with the performance also. There is an extra big draw tube on the DDS, a scope which I would like to acquire an example of someday but don't currently have. It's advertised as being useful for objectives that don't need oculars in photomicrography, apparently like these micro Tessars.

I think the longer e.f. lenses might have f stops, and the 72mm is larger than the society screw as well.

There were some little ones with very short focal lengths that look like microscope objectives but with just a slightly different thread, probably made for ciné cameras.