Mounting Schneider/Nikkor/Bronica lenses in Mamiya Press-helicoid?

Hi all - new to the forums. I originally posted this in the Mamiya Super 23 flickr group, but got no response, maybe someone here has any experience?:

I found a very interesting topic on photo.net about adapting Bronica (and other lens elements) to the Mamiya press helicoid, as they are designed for a standard copal 0 shutter.

http://photo.net/medium-format-photography-forum/00Vh6C

I also found this example of an Schneider 150mm Xenar 5.6 lens, inserted into a Mamiya 150mm:

http://www.rockycameras.com/nice-sc...s-universal-super-23--600se-12999-36742-p.asp

And this with a Schneider Xenar 4.5:

http://www.rockycameras.com/nice-sc...s-universal-super-23--600se-12999-36743-p.asp

I understand that you lose rangefinder focusing with the modifications described on photo.net (Bronica lenses), but does the same apply to these Schneider adaptions? Does anyone know how much work this requires, and have any experience with it?

Could I mount e.g. this multicoated Nikon 150mm 5.6 in an Mamiya 150mm mount, or is the throat of the focusing helicoid too narrow? Even if lose rangefinder focusing, I still think it could be useful with an updated lens for landscapes e.g., without having to invest in a full 4x5 setup.

http://www.ebay.com/itm/Nikon-nikko...6954?pt=Camera_Lenses&hash=item19f01e8f1a

Thanks for any suggestions!

What is the reason to do this? Mamiya lenses too hard to find?

No, there are plenty lenses on the used market. I bought a 150mm (old type from the 1960s) on ebay, but the shutter is not working. I considered trying to repair it, but came to the conclusion I might as well try to upgrade both shutter and lens, if it is feasible.

I did a similar thing using a Graflex XL board. In an attempt to fabricate a more compact Camera.
HA! I'd like to say it's an ongoing project but the ongoing part seems to have lapsed due to lack of interest on my part.

Hmm... I considered Graflex XL lenses too. For now I managed to remove the retaining nut from the back of the lens using two screwdrivers. The Polaroid 600 SE repair manual suggest a special lens spanner, but fortunately it wasn't neccessary. The lens and shutter then falls out easily from the helicoid, just unscrew the PC-cord connector.

A few measurements of the 150mm helicoid - these are approximations, I just used some cheap calipers:

Minimum focal flange distance, from film to inner point of lense mount flange at infinity ~ 142 mm

Maximum focal flange distance, at closest focus distance of helicoid ~ 161mm

This can be adjusted with extension rings, which add about 20mm or 40mm each.

Outer diametre of back element of 150mm lens ~ 29mm

Diametre helicoid opening behind flange ~ 45 mm(guesstimate).

I just ordered a Schneider Xenar 150mm f5.6, as it should fit (as can be seen from the photos linked above). From the measurements it seems also e.g. a Schneider Symmar-S 150mm 5.6 should work, if my measurements are correct (back element outer diametre 40,5mm), however the APO Symmar will probably not (back element diametre 46mm). My goal is to achieve rangefinder focusing with the Xenar. I guess it should be possible by shimming the lens... I will let you know how it goes.

Here is the helicoid with the lens removed:

It arrived!

And here it is. I tried mounting the Xenar directly to the helicoid (like in the pictures from "Rocky Cameras" linked above), however the focus was clearly off compared to the Mamiya 150mm silver type. After adding the locknut which came with the lens to the front of the flange, it -almost- has the same focus point as the original lens, which I guess means rangefinder focusing could be possible. It also means the bare helicoid has a flange distance of less than 142,6 mm (Xenar). My guess would be about 140mm? I just need to find some shims to calibrate it a bit more. I'm checking focus using a 15 megapixel 500d with some macro rings and a pentax 645 adapter (!), so I might be too critical. At f8 it is almost perfect. Now I just need a graflok mount and graflok 4x5 back to test

I might be spamming the thread, but I hope this is useful for others also. Maybe I posted in the wrong location - if so mods might want to move it to Camera Modifications. Anyway... I just received a Schneider Symmar S MC (multicoated), which has a back lens diameter of 40,5mm, and it fits the Mamiya 150mm helicoid with a millimeter to spare. You need to remove a small black metal ring/tube (which can be done by hand), see the picture below, and then there is about 1mm wiggle room (marked by red in the picture), but it works! Pretty cool to have a 1990s lens on a 1960s camera! I will try to calibrate it for the rangefinder, and also check sharpness vs. the Mamiya "blue dot" 150mm. Unfortunately the APO Symmar has a back lens diameter of about 46mm, and will not fit without enlarging the throat further.

Mounting an Apo 150mm had been done. see in photo.net where one can download from dropbox a conversation.

Rodenstock Apo Sironar-N in MUP-150mm helicoid.
First trial: No need to start until rear lens had been shaved. Its almost 42mm. i think if its shaved by 0.5mm it should engage 41mm. Am i right? I could mount with force and afterwards: 1. sticky when rotating. rear lens in contact with inner tube-thread. I dont know if element is engaged at least partly in copal 0 back -thread, since i could turn without the element wobbling up on one it must be engaged at least partly.
Tried to compare with 150mm blue fully open. Have both M and G-Super 23. Meanwhile when working with the shutter i made a mistake or apertures were sticking at f8. when looking from back i could see two blade disengaged but not the normal way. tip of blades could slip out from the plate were ontop. by finding the best position with rotating aperture-wheel i could put the blade into position. but later when turning ring they were not moving central-symmetric anymore. maybe had to do with mthe fact i removed some rings and shouldnt have rotated then.
then i gave up after trying to open from back later also opened front but i didnt see aperture-access which must be from back.
the i could open the last screw. i killed it beforehand...
so i left aperture-problem alone since i needed copal 0-shutter anyhow for Pinhole-system by skinkfoto.
Later when testing focus(some rings still removed i couldnt fing positions for tiny screws) i a save shutter-blade also being disengaged.
at that moment i could only check focus on both cams and compare with 150mm blue.
It is very sharp fully open but could only recognize with right-angle-loupe. the latter removed and peak-loupe checked.
I think the reason why apo sironar is not on this lever could be the fact that rear-element is not close enough to the front lenses.
Must now waiting till i will get a MU for parts. S23-G needs tripod-mount screw and other elements missing. Then i will go to repairman to do also the saving.
Must do infinity test when Apo-lens is mounted properly.
Biggest surprise was when switching from one cam to the other
3m subject was rather inbetween 3 and 5m. so needed extension. This would meen screen must be shimmed, Am I right?

I will love the day when i can use 150mm symmar with Zoerk Multifocus on Hasselblad 203 FE. at the moment its Mamyia RZ67 -mounted so without helicoid. Dont have it in my hands.

Möunting trial Rodenstock Apo-Sironar N in 159mm MUP helicoid.
After removing the mentioned and shown ring. O-shape with tiny slit i would then shave rear element at least by 0.5mm. hope 41mm is enough to reach back-thread enough. I m am not sure but confident i reached it before shaving but couldnt rotate in totally. when helicoid is rotating its sticky. Then compared sharpness with 150mm Blue. On G-cam coarse GG without fresnel didnt show enought details but on M-cam S23 with right-angle finder. If no details must be shown even focussing is a dream.
Since i killed Copal O-shutter not only aperture blades but finally also shutter-blade i couldnt stop down to compare. Will get new Copal 0 and after shaving is done will restart calibrating. and comparing scales. Have only feet-scale on 150 helicoid(damn...) Added not Meter-markings.
Was very suprised on S23-G that viewfinder and GG showed precise 3m-focuspoint but 150mm blue-helicoid was extended between 3 and 10m meaning showing at least 4m. Shouldnt then added shim to GG-fresnel/GG? Will do further testings also real infinity when i have second 150mm Blue soon.
Need a very good loupe since my 10x Peak has too much disturbing scales, some are not visible anymore. maybe they can deliver such scale-glasses-elements, do they? Which stroing loupe with neckstrap can you advise?
NB: Just have bought L-adapter for MUP-lenses from rarecameraadapters.
Zoerk must have a HB mount for 20x(x)-cam of his multifocus-unit instead of RZ67-mount. certainly with tube/helicoid. Will get 150mm symmar multifocus for RZ67. Dont yet have cam.