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Nikkor-O 55mm f1.2: how to focus?
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PostPosted: Fri Sep 06, 2019 11:01 am    Post subject: Nikkor-O 55mm f1.2: how to focus? Reply with quote

Hi,

I have bought a Nikkor-O 55mm f1.2 CRT lens, which comes with a M39/L39/Leica screw mount.

I am trying it out on a Nikon Z by using a L39->Leica M + Leica M->Nikon Z adapter combination.
The Leica M-> Nikon Z adapter has a small helicoid, which I can turn to move forwards and backwards the lens.

However with this combination I cannot focus closer then 2-3 meters. In order to close-focus I have to almost completely unscrew the lens, which I do not like much (the closest focusing distance I can get is around 25 cm).

Can you suggest another solution to achieve a similar of better focusing range but without the need of unscrewing the lens?

Thanks.


PostPosted: Fri Sep 06, 2019 12:32 pm    Post subject: Reply with quote

M39 extension tubes or L39 extension tubes or Nikon Z extension tubes.


PostPosted: Fri Sep 06, 2019 3:27 pm    Post subject: Reply with quote

What VO said. I'm curious, though -- does this lens have any scale markings that indicate minimum focusing distance? If so, does this number correspond with the 2 to 3 meters you're seeing? Perhaps it isn't intended for close focusing?

Does this lens focus correctly at infinity? If so, I'm inclined to think this lack of close focusing performance is just the nature of the lens. Or perhaps the camera it was originally intended to work with has a means by which closer focusing can be achieved.


PostPosted: Fri Sep 06, 2019 4:44 pm    Post subject: Reply with quote

Nah, use a M39-M42 ring, a M42 focusing helicoid, a M42-Nikon-Z camera adapter (Rafcamera has it)
This is how I do it (except the Nikon-Z, as I have none...yet)


PostPosted: Fri Sep 06, 2019 6:35 pm    Post subject: Reply with quote

kds315* wrote:
Nah, use a M39-M42 ring, a M42 focusing helicoid, a M42-Nikon-Z camera adapter (Rafcamera has it)
This is how I do it (except the Nikon-Z, as I have none...yet)


Indeed, an M42 helicoid with matching adapters is the way to go, I do so combined with a flat m42 Sony E adapter. Do check the internal diameter of the helicoid though, some have internal baffles that won't fit the long m39 thread of the lens.


PostPosted: Fri Sep 06, 2019 9:04 pm    Post subject: Reply with quote

kds315* wrote:
Nah, use a M39-M42 ring, a M42 focusing helicoid, a M42-Nikon-Z camera adapter (Rafcamera has it)
This is how I do it (except the Nikon-Z, as I have none...yet)


Btw. this album was shot using such a contraption (but with a very similar CRT f1.2 54mm lens, made to substitute the CRT-Nikkor):
https://www.flickr.com/photos/kds315/albums/72157667385142689


PostPosted: Fri Sep 06, 2019 10:09 pm    Post subject: Reply with quote

Want infinity? Can lens held close to camera focus infinity? L39 to e + e to z adapter may be shortest adapter possible non-custom excluded.a


PostPosted: Fri Sep 06, 2019 10:27 pm    Post subject: Reply with quote

visualopsins wrote:
Want infinity? Can lens held close to camera focus infinity? L39 to e + e to z adapter may be shortest adapter possible non-custom excluded.a


You are correct for normal m39 lenses. This lens however has a very long m39 thread. The combination of m39-m42 adapter and an m42 helicoid allows the rear of the lens to move inside the helicoid. This gives you far more flexibility than a direct m39 to E adapter. In that case any helicoid must be behind the rear of the lens. My Pentax m42 helicoid fits over the whole m39 section, on my Sony A7 I get well past infinity.


PostPosted: Sat Sep 07, 2019 11:34 am    Post subject: Re: Nikkor-O 55mm f1.2: how to focus? Reply with quote

wolan wrote:
Hi,

I have bought a Nikkor-O 55mm f1.2 CRT lens, which comes with a M39/L39/Leica screw mount.



Which of these is it?
L39/Leica screw mount is a rangefinder mount with 28.8mm registration/rear flange distance IIRC
M39 is the same thread (M39 at 24tpi not the often quoted & very similar m39x1) It's used for many enlargers as well as a few SLR mounts. The enlarger versions have variable registration while the SLR versions are similar to M42 (45.46mm).

The correct mounting for focusing will depend on which registration the lens has.


PostPosted: Sat Sep 07, 2019 12:07 pm    Post subject: Re: Nikkor-O 55mm f1.2: how to focus? Reply with quote

DConvert wrote:
wolan wrote:
Hi,

I have bought a Nikkor-O 55mm f1.2 CRT lens, which comes with a M39/L39/Leica screw mount.



Which of these is it?
L39/Leica screw mount is a rangefinder mount with 28.8mm registration/rear flange distance IIRC
M39 is the same thread (M39 at 24tpi not the often quoted & very similar m39x1) It's used for many enlargers as well as a few SLR mounts. The enlarger versions have variable registration while the SLR versions are similar to M42 (45.46mm).

The correct mounting for focusing will depend on which registration the lens has.


As I mentioned before, it has a long m39 thread, not an L39 rangefinder mount. It is an industrial lens designed for 1:5 magnification (the second version of the lens is at least, and is marked as such).



A quick smartphone photo shows the lens with its 15mm long M39 thread, in this case with an M39-M42 ring installed.

When screwed directly into an L39-Sony E adapter on my A7 the focus is just past infinity. I used it with a Pentax M42 helicoid and flat M42-Sony E adapter:


In this setup I need the helicoid and adapter combination to be 23mm long for infinity focus. Including the 18mm register distance of the Sony E mount that would result in a 41mm register for the lens itself, measured from the start of the M39 thread.


PostPosted: Sun Sep 08, 2019 4:49 pm    Post subject: Reply with quote

NIKKO-O normally comes with this (->) ring (convenient for mounting the lens) 5.04mm thick


CMHT=Camera mount for Helicoid Tube (basically simple M42->E mount adapter) 1.5mm thick
H=M42-M42 helicoid (this one is 11mm - 15mm)
L39->M42 ring (this one is MAFCAMERA made in England) 2.04mm thick



Samples > https://pbase.com/kkawakami/nikkor_o_55mm_f12


Last edited by koji on Sun Sep 08, 2019 8:42 pm; edited 1 time in total


PostPosted: Sun Sep 08, 2019 7:30 pm    Post subject: Reply with quote

Glad to hear my quick measurement and yours roughly match. Indeed, if you have the original m39 locking ring you may use it to finetune the length of the M39 thread so that with a short helicoid you reach infinity precisely at its minimum length. Using no lock ring you can use a longer helicoid though, that will give you a longer focus range.. The Pentax one I mentioned is 17-31mm in length.


PostPosted: Sun Sep 08, 2019 9:28 pm    Post subject: Reply with quote

koji wrote:
NIKKO-O normally comes with this (->) ring (convenient for mounting the lens) 5.04mm thick


CMHT=Camera mount for Helicoid Tube (basically simple M42->E mount adapter) 1.5mm thick
H=M42-M42 helicoid (this one is 11mm - 15mm)
L39->M42 ring (this one is MAFCAMERA made in England) 2.04mm thick



Samples > https://pbase.com/kkawakami/nikkor_o_55mm_f12


Thanks a lot. I have mounted the lens on the camera using a M42->Nikon Z adapter with helicoid and a M39 to M42 ring adapter to mount the lens on the adapter. The longest focusing distance is roughly 80 cm, but at least I can start using the lens.

However I have ordered in the meantime the M42-M42 adapter with helicoid like the one you use.

Thanks again.


PostPosted: Sun Sep 08, 2019 10:42 pm    Post subject: Re: Nikkor-O 55mm f1.2: how to focus? Reply with quote

dickb wrote:
DConvert wrote:
wolan wrote:
Hi,

I have bought a Nikkor-O 55mm f1.2 CRT lens, which comes with a M39/L39/Leica screw mount.



Which of these is it?
L39/Leica screw mount is a rangefinder mount with 28.8mm registration/rear flange distance IIRC
M39 is the same thread (M39 at 24tpi not the often quoted & very similar m39x1) It's used for many enlargers as well as a few SLR mounts. The enlarger versions have variable registration while the SLR versions are similar to M42 (45.46mm).

The correct mounting for focusing will depend on which registration the lens has.


As I mentioned before, it has a long m39 thread, not an L39 rangefinder mount. It is an industrial lens designed for 1:5 magnification (the second version of the lens is at least, and is marked as such).

pic

A quick smartphone photo shows the lens with its 15mm long M39 thread, in this case with an M39-M42 ring installed.

>>>>>>>When screwed directly into an L39-Sony E adapter on my A7 the focus is just past infinity. I used it with a Pentax M42 helicoid and flat M42-Sony E adapter:

pic

In this setup I need the helicoid and adapter combination to be 23mm long for infinity focus. Including the 18mm register distance of the Sony E mount that would result in a 41mm register for the lens itself, measured from the start of the M39 thread.


Thanks!