For Tristin and all: 105/1.8 posted on "1001 Nights"

[Akira]

Here's one of the TVCMs of the "Persimmon Seeds":

https://www.youtube.com/watch?v=rsRMBcJnatk

And hiere's a short factory tour:

https://www.youtube.com/watch?v=BL0Rrcjw0VI

Please don't ask for the translation into English!   

[David H. Hartman]

I wonder why so many refer to these 105mm AIS Nikkors as Gauss type lenses when Nikon lens designers refer to them as Xenotar-type type lenses...

"I think you will immediately see that the lens utilizes typical Xenotar-type optics." --Haruo Sato, Tale 59, (Figure 1) "

"Take a look at the cross-section of the AI Nikkor 105mm f/2.5 lens (Fig. 2.). This design is based on the Xenotar-type lens (5 lenses, 4 groups) with thick, convex lenses, rather than the Sonnar type with its many asymmetric components." --Haruo Sato, Tale 5, (Figure 2)

[richardHaw]

Hello, David.
I think it's because they look similar at first glance?

[Roland Vink]

Mass production of the lens began in the fall of 1979, and the lens was finally released in September, 1981.
In production for two whole years before being released? That doesn't seem right. Maybe prototypes were made in 1979 and the design finalised, then a year or so for tooling up before production started. I had a slightly earlier release date of March 1981 but this sort of detail is hard to verify.


... Xenotar-type optics. It was explained as a sort of hybrid with the front group of Gauss type and the rear group of Topogon type
I don't know what the technical difference is, they two types are clearly related. Maybe the Gauss type consists of three elements: convex, then convex/concave (cemented or closely associated). The Topogon has two elements, convex like the gauss, and then concave instead of the gauss convex/concave.

That may be why many 50mm lenses are described as "double-gauss" designs, with gauss groups front and rear:

[pluton]

It seems, after looking at the cross-sections, that the old 105/2.5 can casually be described either as a "Gauss-type"---for it's single Gauss-appearing group in front, or it can be more accurately described as a Xenotar type.  Noted.