The Big Sankyo Kohki/Komura Thread

calvin83 · Joined: 12 Apr 2009 Posts: 7554 Location: Hong Kong

You may use a Nikon F mount or Canon EF helicoid if you are unsure...

John Shriver · Joined: 24 Dec 2009 Posts: 193

I have the Komura 100/1.8, and it has the normal 46mm Unidapter threads. Easiest way to get a Unidapter adapter is to buy one of the 135mm Komura lenses with the one you want on it!

mrlizard · Joined: 05 Mar 2024 Posts: 8

BrianSVP · Joined: 09 Jun 2023 Posts: 301 Location: Philadelphia

If it's a unidapter ring, it includes the entire silver colored assembly. Not sure what's going on twith the brass ring narrower than the other screw mount it's in, but perhaps it's a bespoke mod? The unidapters exist in several mounts but are fairly rare and can be pricy. Right now, the only one listed on eBay is to Konica AR and costs $40:
https://www.ebay.com/itm/402821053716

If you want to go to m42, your best bet might be to search for Komura lenses on eBay, find one that's listed on m42 that uses the unidapter, cannibalize the adapter, and resell the lens. This link might be of use:
https://allphotolenses.com/lenses/systems/c_69.html

kiddo · Joined: 29 Jun 2018 Posts: 1123

There would be an option if RAF camera would be make some adapters for these lenses , 4meters MFD is way to long, I was using a Nikon thin ring to get closer , but I believe a m42 adapter to use a helicoid would be easier to use

mrlizard · Joined: 05 Mar 2024 Posts: 8

Thank you for the suggestions. I would give the unidapter cannibalisation a go but I can't seem to get this mount off. Feels like it's welded on. Once the screws are all taken out it shouldn't be stubborn to come off should it?

I've confirmed that the thread is m44. I would love to find a brass ring thing like in the picture that would step it down to m42.

Enjoying it as a paperweight for the time being

BrianSVP · Joined: 09 Jun 2023 Posts: 301 Location: Philadelphia

Try putting a few drops of acetone on the adapter to loosen any threadlocker that might have been applied. If that doesn't work, try putting the lens in an oven well away from any heating element/flame and bring it up to its lowest setting (175F/80C or so) and let it heat for 10-15 minutes, then holding it with some hot pads/gloves, try to loosen it. Often, these methods are enough to detach a stubborn ring.

Another option if this doesn't work: try measuring the inner diameter of the M44 ring on yours. If it's close to m42, you might be able to get an m39 to m42 adapter ring like the one in the link below and glue/epoxy it in place. similarly to the brass ring in the pic you provided. Depending on the flange focal distance of the existing m44 adapter, you may or may not be able to achieve infinity, but at the very least, you'd be able to mount it for closeups.

https://www.amazon.com/Packs-Adapter-Ring-Focusing-Helicoid/dp/B003MEO82M

mrlizard · Joined: 05 Mar 2024 Posts: 8

Thank you for the suggestions. I've stripped down what I can and have tried heating this in the oven in the hope that the part in red would then separate off. No such luck. Made me wonder if the part in green is just one solid piece. Will wrestle with it some more..
#1

#2

#3

stevemark · Joined: 29 Apr 2011 Posts: 3754 Location: Switzerland

mrlizard · Joined: 05 Mar 2024 Posts: 8

Managed to separate the m44 mount after a prolonged struggle. Filled the screw holes with acetone as suggested and found a bottle opener that was the right shape to brace against the 2 protruding teeth things inside. After a lot of effort and swearing trying to twist the mount it made an interesting squeak. Kept adding acetone and gradually twisted it round a couple of times. Realised then it wasn't a screw thread and managed to slowly pry it off bit by bit.

Excited to get the thing off. Hoping I can find something else to slot on. I'll probably discover I've just done the easy bit..

BrianSVP · Joined: 09 Jun 2023 Posts: 301 Location: Philadelphia

Ha, congratulations! Adjustable flanged ring setups with set screws like that are commonly used on T2 adapters, so if you can find one with the right diameter flange, you might be able to replace the m44 with an m42 scavenged from such an adapter, then from there, the world's your oyster.

EDIT: Actually, let me know the depth and diameter measurements of the flange there, as I have a few T2 to m42 adapters lying around, and if I find one that fits, I can just send it to you.

mrlizard · Joined: 05 Mar 2024 Posts: 8

Ah thank you, that would be amazing if you have one that fits! M42 would be a dream.

It looks like 54mm diameter and 6mm deep if I'm measuring the right bits - pics here in case