Quote Originally Posted by E. von Hoegh View Post
The 50/2 Nikkor H for the Nikon SLRs is a 6 element double Gauss type, and is excellent. The 50/2 Nikkor H-C for rangefinders is not the same lens, it is a Sonnar clone.

Edit - As for the Industars, the I-50 is an improved version of the I-22, both are f:3.5 Tessars. The I-61LD is an f:2.8 Tessar using a lanthanum glass element for better correction.
You know, it's funny that you mention the difference between those two Nikkor lenses. I had gone to my copy of The Nikon Manual earlier in the day to reference the specs page on the F-mount Nikkor-H 50/f2, and I noticed that it was a double Gauss design, and not a Sonnar like I had understood the rangefinder version to be. That double Gauss design is a Planar, is that right?

I had known that the I-22 was a Tessar f3.5 clone, and I had known that the I-50 was an improved I-22 (though I'm still not clear on how it was improved), but I did not know that the I-61 was a Tessar f2.8. I've read that f2.8 is about the limit of the Tessar design, and that it's really better suited as a f3.5; does the lanthanum glass make an improvement on that?

And, did Zeiss ever make a Tessar in LTM?