Nikkor-T 10.5cm f/4

[Akira]

Rick and Roland, thank you for the details of the aperture blades.  The harsh shape of them might be both due to the even step on the aperture control ring and the low-cost design.  Leiz Elmar 90/4.0 had many more aperture blades and uneven step but perfectly rounded openings at any settings.

[Roland Vink]

Even step aperture rings may be a little harder to design since the difference in moving the aperture blade from f/4 to 5.6 is much greater than from f/16 to 22, even though both are one stop apart, but that is a question of designing the cam to move the blades correctly in addition to the shape of the blades.

The shape of the aperture really is quite curious. From f/4 the opening is circular but by half a stop down it starts to get a saw-tooth shape as the "knees" along the edge of the aperture blades start to appear. Half a stop either side of f/8 the saw-tooth pattern is more or less a regular star shape before becoming a saw-tooth again. By f/11 the opening is a simple 9 sided polygon. It is the only f-mount Nikkor that is like this.

[Akira]

I observed similar behavior of the aperture blades on 50mm/f2.0 Summicrons made in Canada in the 80s.

Interestingly the aperture blades of Leica lenses since that time was shaped so that they make a perfectly round shape when set at the smallest aperture, possibly in order to minimize the diffraction.

[richardHaw]

This is a very quirky lens. I hate it but at the same time, i also love it 

i hope i can find a cheap S-mount version

as for the hood, wish me luck!

[richardHaw]

https://richardhaw.com/2018/01/06/repair-nikkor-t-10-5cm-f-4/

i just updated this article with plenty of new pictures.

wow, this lens is superb! i didnt realize it until i used it with film. it has a nice balance of sharpness while not losing the delicateness of its rendering. i liked it so much that the S-mount version is heading its way to my house hopefully by tonight 

[Roland Vink]

S-mount is rare compared to the F-mount version. Send me the serial number when it arrives, and if it is engraved LMIJ

Both versions were made in parallel and share the same block of serial numbers - I guess the optical unit with serial number was assembled first, and then put into one mount or the other

[richardHaw]

S-mount is rare compared to the F-mount version. Send me the serial number when it arrives, and if it is engraved LMIJ

Both versions were made in parallel and share the same block of serial numbers - I guess the optical unit with serial number was assembled first, and then put into one mount or the other

S/N: 410852

not sure if its MIOJ 

[Roland Vink]

Thanks!, It won'd be Made in Occupied Japan (MIOJ), it's too late for that - one of the last rangefinder lenses made - but some early lenses are engraved LENS MADE IN JAPAN (LMIJ). Your serial number is relatively late so it probably doesn't have it.

[richardHaw]

Thanks!, It won'd be Made in Occupied Japan (MIOJ), it's too late for that - one of the last rangefinder lenses made - but some early lenses are engraved LENS MADE IN JAPAN (LMIJ). Your serial number is relatively late so it probably doesn't have it.

Sorry, been collecting MIOJ lenses so that stuck 

Not sure if its LMIJ, doesnt look like it. i will check when i get home

[richardHaw]

Thanks!, It won'd be Made in Occupied Japan (MIOJ), it's too late for that - one of the last rangefinder lenses made - but some early lenses are engraved LENS MADE IN JAPAN (LMIJ). Your serial number is relatively late so it probably doesn't have it.

I cant find the LMIJ mark

[richardHaw]

https://richardhaw.com/2020/04/18/repair-nikkor-t-10-5cm-f-4-s-mount/

just published the S-mount version

[Roland Vink]

Looks like a lovely lens! One difference between the F-mount and S-mount versions that is worth noting: the F-mount lens focuses much closer - to 0.8m, while the S-mount version only focuses to 1.2m. I suppose the focus range of the S-mount version was limited to prevent parallax errors with the viewfinder at near distances. On the other hand, the lens is a 3-element Cooke triplet, a symmetrical design well suited for closeups, so the F-mount version was allowed to focus closer.

[MarcelvanEngen]

By luck I got hold of a Nikkor 10.5 T 407267, including caps, hood and case. And by luck it was here in the UK. Strangely enough the original quality note shows a different number. (Anybody has a quality control note with my number on it? 

 I am actually surprised by the quality.
This picture of Pepper is in my view absolutely pin sharp and the rendering was a surprise.
It looks weird on a Df but the result counts.
Sweet lens.