NIKKOR-N 35mm f/1.4 Prototype

[RonVol]

Here's a very rare photo from 1970 of the prototype Nikkor-N 35mm f/1.4 with serial #254003.
Nothing obvious stands out when comparing this example to a production version.

[Akira]

Ah, this should be the one with the Thorium glass.  Never seen the image of it.  Thanks, as always, for sharing, Ron!

[Erik Lund]

Very vintage Thanks for posting!

[pluton]

Ah, this should be the one with the Thorium glass.  Never seen the image of it.  Thanks, as always, for sharing, Ron!

I have read that the first production Nikkor-N also carries the hot glass and that the Mk2 "K" revision eliminated it.

[Akira]

I have read that the first production Nikkor-N also carries the hot glass and that the Mk2 "K" revision eliminated it.

You mean, all versions with the metal hill-and-dale focusing rings have the Thorium glass elements?

[chris dees]

According to Rolands DB mine is from early 1971 and it is the 9-blade thorium one. I guess second generation. Beautiful chipped by Erik.
It has a strong yellow cast but it's not always the same.
The examples are from the central square in Antwerp.

[richardHaw]

that amber tint might come into handy with BW film 

[pluton]

You mean, all versions with the metal hill-and-dale focusing rings have the Thorium glass elements?

Yes, that is my assumption. The "C" version on Roland's list. 

[Roland Vink]

You mean, all versions with the metal hill-and-dale focusing rings have the Thorium glass elements?

Yes that's right, the glass material changed with the New Nikkor (K) version, see http://www.nikkor.com/story/0027/ :

This lens has been used to date since its first introduction in 1971 through changes in the lens barrels and the adoption of what was then the latest super-integrated coating technologies; changes were also made to the optical system at the time when the lens barrel design was changed to the NEW-Nikkor. Though the basic lens construction remained unchanged, the glass material and the lens curvature were changed by Teruyoshi TSUNASHIMA, to improve the performance at open aperture.

[Akira]

Chris, thanks for sharing the image of your lens.

Keith and Roland, thanks for the answer.  I'm well aware of the 1001-night article, but the Thorium glass is not mentioned there.  Probably because the Japanese people are in general too sensitive to anything radioactive, including me.