Nikon 105mm f/4.5 UV-Rayfact (and its older twin, the Nikon 105/4.5 UV-Nikkor)

[dabateman]

The UV-Nikkor was released years after Nikon had introduced the AiS aperture operation on their lenses.

 

Thats really good to know. Then other one I saw would be a fake. Thank you. I will watch out for that.

[nfoto]

According to my sources, Nikon released the UV-Nikkor 105 in 1984. So it always has been an AiS lens.

 

It shares the outer casing with the Micro-Nikkor 105mm f/4 up to the 'nose' of the latter, which has a retractable lens hood built-in that the UV-Nikkor lacks. Thus I guess any fake 'UV Nikkor' might be a relabelled Micro 105/4.

[diant]

May be its scheme will be interesting for somebody. This UV 105mm lens is said to have a 6/6 design. But I saw the two versions of its drawing.

 

The first one:

 

The second one:

 

The second one appears to have 6/5 design, but I guess that it is only visual appearance (coarseness of a drawing), and in reality G5 and G6 elements aren't glued.

 

As quartz plays a role "flint" in such fluorite-based lenses and as the manufacturer declare 3 CaF2 elements and 3 quartz elements, it is obviously that G1, G4 and G6 should be quartz and G2, G3 and G5 - fluorite. It is very fortunate (and may be was consciously desired) that the first and the last elements are of quartz, not of CaF2. Latter is much more delicate and doesn't like any touchings, cleanings, weather's influences etc.

 

Of course fluorite may be guarded by a coating, but I don't know about it nothing as concerning UV 105mm Nikkor.

I can say only that early fluorite refractors (end of XX century) had uncoated CaF2 lens, and even early Japanese Takahashi fluorite refractors (one of the best in the world) had a uncoated one. I may guess that the coating of fluorite may be not so easy thing and was adopted not long ago.

 

And the later consideration.

The refractive indexes of fused silica and CaF2 are very low, therefore it is very hard to fix a field curvature with such elements only.

So I guess that even at 105mm of focal distance this lens wide open should lose much of its sharpness to the edge of 36x24mm frame.

With a shorter focal distance the situation are become worth. And I think that it is almost impossible to design Q/F lens with a focal distance 80mm or shorter, which will cover full frame with any acceptable sharpness through the field without closing its aperture to a little hole.

[Andrea B.]

That is cool lens diagram for the UV-Nikkor. Very happy to see it posted. Thank you.

 

It is easy enough to test (informally) whether there a loss of sharpness at the edges in full-frame when the UV-Nikkor 105 is set at f/4.5.

 

But, alas, I am monumentally lazy about setting up sharpness tests. :lol:

[nfoto]

The UV-Nikkor is sharp across the entire frame.

[Andrea B.]

Thankee !

[JCDowdy]

As of April 2020 the manufacture of Rayfact products was transferred back to Nikon Corporation.

 

My bookmark to the Tochigi Rayfact pages was also moved.

 

Info now found here: https://www.nikon.com/products/industrial-lenses/lineup/uv/

 

The current incarnations of the 50 mm F2.8N, 63 mm F2.8N EL-Nikkors are here also: https://www.nikon.com/products/industrial-lenses/lineup/low-magnification/

[Stefano]

A curiosity: CaF₂ is very slightly water-soluble (0.016 g/L at 20°C according to Wikipedia), so if this lens has CaF₂ elements in the front or rear, could they be attacked by water? (Although, I have to admit, the solubility is very low).

 

Edit: just realised Anton wrote that the front and rear elements are made of fused silica, so there's no risk of water ruining them.

 

In general, almost all deep UV materials (such as MgF₂ and LiF) are slightly water-soluble. Fused silica and sapphire are not, but sapphire is birefringent. There isn't much choice for wavelengths below 300 nm.

 

[Also, is it really impossible to make a material more transparent to deep UV than LiF? That's such a pity].

[Guest]

[Also, is it really impossible to make a material more transparent to deep UV than LiF? That's such a pity].

 

A thousand years from now we will have lens elements made of ‘hot air’!

[Andrea B.]

As long as it passes UV, I'm in......

[diant]

The UV-Nikkor is sharp across the entire frame.

Well, it means that 105mm is enough focal distance to correct all aberrations at Full Frame with Q and F glasses.

UFAR-12 2,5/41mm Q/F lens (I worked with it some time ago) with probably 8-elements design has a circle of coverage only half-FF (18x24mm) and with evident vignetting.

[Andrea B.]

Anton, do you happen to know the flange focal distance of that UFAR-12 41/2.5??

[diant]

Anton, do you happen to know the flange focal distance of that UFAR-12 41/2.5??

Yes - 30,36mm. So I had to re-thread it from M42x1 to M39x1 for I can use it with old rangefinder cameras with back focal distance much shorter then ~45mm.