Possible emulation of CRT Nikkor?

[Akira]

Mr. Akiyama, the owner of the famous "Red Book Nikkor" website, revised the sections dedicated to Nikkor-O 55/1.2 a.k.a. CRT Nikkor.  He added a couple of images of the prototype of the CRT Nikkor called "Nikkor-O Auto 50mm f/1.2-1.4" displayed during the special exhibition of rare prototypes of Nikkor lenses held at the Nikon Museum in Shinagawa, Tokyo (scroll way down):

https://redbook-jp.com/redbook-e/record2/crt.html

What interests me is the description for the lens pictured in the second image from the bottom of the linked webpage:

https://redbook-jp.com/redbook/record2/f260.jpg

Interestingly, the cross section of the CRT Nikkor sans the front element resembles very closely to that of the ubiquitous Nikkor Auto 50mm f/1.4:

https://redbook-jp.com/redbook/record2/f320.jpg

https://imaging.nikon.com/history/story/0044/index.htm

Then I wonder if you could emulate the CRT Nikkor using 50/1.4 lens with a closeup attachment of an appropriate diopter?

[Michael Erlewine]

If you figure out how to do that, be sure to let me know. LOL. Getting that kind of clarity would be tough, IMO.

Try out the new Voigtlander APO-Lanthar Macros for Sony E-Mount, the 65mm and 110mm.

[Akira]

If you figure out how to do that, be sure to let me know. LOL. Getting that kind of clarity would be tough, IMO.

Try out the new Voigtlander APO-Lanthar Macros for Sony E-Mount, the 65mm and 110mm.

MIchael, an achromatic (2 elements glued together) closeup diopter might better the image quality to some extent.   

Your images have already proved the amazing performance of the new Apo-Lanthars!

[Michael Erlewine]

MIchael, an achromatic (2 elements glued together) closeup diopter might better the image quality to some extent.   

Your images have already proved the amazing performance of the new Apo-Lanthars!

Well,, try it out and tell me how to do it.  As you know, like yourself, I love the Nikkor "O" lens and look for ways to extend its usefulness.

[Akira]

Well,, try it out and tell me how to do it.  As you know, like yourself, I love the Nikkor "O" lens and look for ways to extend its usefulness.

I will whenever I get the chance.  And, yes, I love Niikor O.  I've moved through cameras of different brands, but CRT has always been adapted to all of them!

[Michael Erlewine]

I will whenever I get the chance.  And, yes, I love Niikor O.  I've moved through cameras of different brands, but CRT has always been adapted to all of them!

Putting it on the Z7 with Leica (M39) thread adapter and some extension gives you more total range for the lens.

[Birna Rørslett]

"A little more" range ... too far away from its designated 1:4 to 1:5 magnification (approx.) makes all parts of the image frame except the very centre go to mush.

[Michael Erlewine]

"A little more" range ... too far away from its designated 1:4 to 1:5 magnification (approx.) makes all parts of the image frame except the very centre go to mush.

True, but don't go THAT far and it still works well, IMO.

[Bruno Schroder]

Is this the config you have in mind, Akira?

[Roland Vink]

Interestingly, the cross section of the CRT Nikkor sans the front element resembles very closely to that of the ubiquitous Nikkor Auto 50mm f/1.4 [...]

Very interesting, I think you are right! The prototype lens does look very similar to the regular production Nikkor-S 50/1.4, and the information card even states "... a normal lens that incorporates a convex lens at the front in order to photograph close-up images ..."
Probably the closest way to replicate the CRT Nikkor is to add one of the close-up diopters such as No.0, 1 or 2. I wonder if the acrhromat No.3 or No.4 would give improved image quality?

In those days designing a lens was very expensive and time-consuming, most ray-tracing calculations were done by hand, or with very primitive computers, so it was easier to modify an existing design rather than build a new lens from scratch. For example the early 200mm Medical Nikkors are based on the regular Nikkor-Q 200/4 lens, and in tale 70, it shows how the Nikkor-H 300/4.5 is just a refinement of the Nikkor-P 300/4.5.

[Akira]

"A little more" range ... too far away from its designated 1:4 to 1:5 magnification (approx.) makes all parts of the image frame except the very centre go to mush.

You could be right, Birna.  That said, the enigmatic 50/1.4 lens, apparently based on Ais 50/1.4, I sold you might be corrected for the close range by putting the front and the rear groups a little further from each other than the original Ais.  So, that could be a good candidate for the experiment.

[Akira]

Is this the config you have in mind, Akira?

Bruno, yes, exactly!

[Akira]

Very interesting, I think you are right! The prototype lens does look very similar to the regular production Nikkor-S 50/1.4, and the information card even states "... a normal lens that incorporates a convex lens at the front in order to photograph close-up images ..."
Probably the closest way to replicate the CRT Nikkor is to add one of the close-up diopters such as No.0, 1 or 2. I wonder if the acrhromat No.3 or No.4 would give improved image quality?

In those days designing a lens was very expensive and time-consuming, most ray-tracing calculations were done by hand, or with very primitive computers, so it was easier to modify an existing design rather than build a new lens from scratch. For example the early 200mm Medical Nikkors are based on the regular Nikkor-Q 200/4 lens, and in tale 70, it shows how the Nikkor-H 300/4.5 is just a refinement of the Nikkor-P 300/4.5.

I agree, Roland.  I also guess the LF Nikkors like 105/5.6 and 135/5.6 share the same optical design with the EL equivalents.

Just like the CRC of Ais Micro Nikkor 55/2.8, you could manipulate the targeted magnification by adjusting the distance between the front and the rear groups.  So, sharing the LF lens designed for infinity and the EL lens designed for larger magnification factors should be possible with the near-symmetric Gaussian design.

[Dr Klaus Schmitt]

Very interesting find Akira!

You might know that there are at least other emanations of this same lens made by different manufaturers? I was happy to find them years ago... (pic (c) Wiki Commons)

[Akira]

Very interesting find Akira!

You might know that there are at least other emanations of this same lens made by different manufaturers? I was happy to find them years ago... (pic (c) Wiki Commons)

Klaus, yes, I do know and have seen other CRT lenses of similar specification like the one made by Kowa.  I know about the JML but cannot identify the one on the left of the image you shared.