converted Meike 3.5mm m4/3 to cmount for Bolex

[Allyn Iwatsuru]

I successfully converted this Meike 3.5mm fisheye to c mount by frankensteining multiple other mounts together. I always wanted a fisheye for 16mm but my only options have been limited to a select few rare lenses that are also quite expensive, but this Meike caught my eye. I had always wondered if converting m4/3 to c mount was possible due the longer focal flange distance so I bought the lens and for $180 I figured I couldn't lose.

IMG_8031.HEIC IMG_8073.HEIC

[Allyn Iwatsuru]

 

[Philip Forrest]

This is pretty cool. How close does the rear element shroud get to your prism?

Phil Forrest

[Allyn Iwatsuru]

19 hours ago, Philip Forrest said:

This is pretty cool. How close does the rear element shroud get to your prism?

Phil Forrest

Not that close, the shroud sits almost flush with the barrel of the mount and the mount isn’t the full length of the c mount threads.

[Patrick M P Donnelly]

There are 4.8, 5.5, 6 and 6.5mm c mount lenses available on fleabay. All but the 4.8mm are for 1 inch sensors, close to S16mm.

The 4.8mm is on its way to me and may be for 1 inch. The distortions are impressive, but the 6.5mm is almost tolerable.

The best rectilinear, moderately affordable, extreme, wide angle lens in C mount, is the Kowa or Navitar 6mm HC series. Some second hand ones have wandered onto our fave electronic flea market. There appear unused. Some seller has compiled all the available video demonstrations of this lens, in the advert. Modesty forbids...

Brand new, the Kowa actually have a wider lens: 4.7mm F/2.4 for a mere $1,079 AUD. Unknown how it draws.

[Marc De Acetis]

Looks so cool! What adapters did you use to finally get to C-Mount?

[Allyn Iwatsuru]

On 5/23/2021 at 8:22 PM, Patrick M P Donnelly said:

There are 4.8, 5.5, 6 and 6.5mm c mount lenses available on fleabay. All but the 4.8mm are for 1 inch sensors, close to S16mm.

The 4.8mm is on its way to me and may be for 1 inch. The distortions are impressive, but the 6.5mm is almost tolerable.

The best rectilinear, moderately affordable, extreme, wide angle lens in C mount, is the Kowa or Navitar 6mm HC series. Some second hand ones have wandered onto our fave electronic flea market. There appear unused. Some seller has compiled all the available video demonstrations of this lens, in the advert. Modesty forbids...

Brand new, the Kowa actually have a wider lens: 4.7mm F/2.4 for a mere $1,079 AUD. Unknown how it draws.

I looked into those and they probably turn out great results, but are a bit expensive for me.

 

On 7/29/2021 at 6:49 AM, Marc De Acetis said:

Looks so cool! What adapters did you use to finally get to C-Mount?

Sorry I never got back to this question. Here are the links to the adapters.

https://www.bhphotovideo.com/c/product/1245026-REG/fotodiox_c_mft_lens_mount_adapter_for.html

https://www.bhphotovideo.com/c/product/889270-REG/computar_VM400_Extension_Tube_5mm.html

[Raymond Zrike]

Those results look fantastic! Not sure why I had never seen this thread before you mentioned it elsewhere.

On 9/18/2021 at 8:53 PM, Allyn Iwatsuru said:

Sorry I never got back to this question. Here are the links to the adapters.

What process did you take to combine the C-to-M4/3 adapter and the extension tube? Did you manage to keep infinity focus (although that isn't much of a concern for something so wide)?

[Allyn Iwatsuru]

5 hours ago, Raymond Zrike said:

Those results look fantastic! Not sure why I had never seen this thread before you mentioned it elsewhere.

What process did you take to combine the C-to-M4/3 adapter and the extension tube? Did you manage to keep infinity focus (although that isn't much of a concern for something so wide)?

Literally just glued the two adapters together hahaha, the c mount extension tube screws into the m4/3 adapter so you don’t have to worry about centering it. Drilling holes for screws would be simple enough and I would do it if I was adapting a more expensive heavier lens. The new mount does actually allow for infinity focus (a little closer, maybe at the 7ft mark off the top of my head) because it’s the adapter flipped upside down so it’s essentially just a m4/3 mount with c mount threads. The reason why it doesn’t hit infinity perfectly on mark is cause I had to file some of lips away thus making it closer to the film plane.

[Raymond Zrike]

Very interesting. If it’s that simple, maybe I could just smoosh together a m4/3 mount and a c-mount in Blender or something and send it off to a 3D printer. I’d have to learn Blender first lol, but anything for art!

I’ll give your method a shot first though. I think the difficult part would be maintaining the accuracy of the focus scale, but personally I just focus through the viewfinder, so this could be viable for some shooting situations.

[Allyn Iwatsuru]

On 5/2/2022 at 6:06 PM, Raymond Zrike said:

Very interesting. If it’s that simple, maybe I could just smoosh together a m4/3 mount and a c-mount in Blender or something and send it off to a 3D printer. I’d have to learn Blender first lol, but anything for art!

I’ll give your method a shot first though. I think the difficult part would be maintaining the accuracy of the focus scale, but personally I just focus through the viewfinder, so this could be viable for some shooting situations.

I entertained the thought of finding a metal shop to fabricate some adapters since I had got a lot of interest from friends of friends, but after short research I found that metal shops typically only do large quantities. That idea was killed quickly. I wouldn’t worry about the focus scaling marks it’s a 3.5mm, if it hits infinity practically everything is in focus

[Raymond Zrike]

I believe 3D printing services are a bit different than a metal shop—from my little bit of research, it seems you can get a small quantity or even just one printed. I was looking at one printing service and they quoted $12 for an aluminum print.

I have another part that I want printed for my Eclair ACL anyways, so I’m going to get that made first and see how it goes. Then maybe will do the c-mount to m4/3 mount!

[Antoine Pret]

That is so good ! Thanks for sharing !

[Allyn Iwatsuru]

Btw to get it to fit on any camera you have to file down that skirt on the rear of the lens body, but on the acl you have to file down a significant amount or it hits where it starts to protrude out for the base of the camera below the lens mount. I’ve fit this lens on a bolex, eclair acl ii and a Beaulieu 2008s. The eclair is the hardest to work with because the handle and the kinoptik viewfinder can be in frame so you have to rotate them back. 

[Ben Lalande]

Wow this is so rad. I assume you shaved a bit off that m43 adapter and put screws through it? How did you nail the right flange distance? Did you just eyeball it? I would be really curious to see if this could also be done with the Laowa 6mm for m43. That would be an amazing linear lens for it. 

[Allyn Iwatsuru]

19 hours ago, Ben Lalande said:

Wow this is so rad. I assume you shaved a bit off that m43 adapter and put screws through it? How did you nail the right flange distance? Did you just eyeball it? I would be really curious to see if this could also be done with the Laowa 6mm for m43. That would be an amazing linear lens for it. 

So I went through a lot of tedious calculations and measurements but then just realized if I inverse the adapter (putting the adapter on the way I currently have it), that inherently makes it the correct flange depth. I want to do the Laowa 6mm as well, I’m waiting for one to pop up on sharegrid so I can rent it and take measurements. There’s two main things I have to look out for, the rear lens element housing fits inside the c mount throat and the outer lens housing clears all the stuff on the turret of a bolex ( the eclair acl also runs into this problem as the base protrudes out below the lens mount).

[Ben Lalande]

This is great man, thanks for the info. Do you have an instagram or vimeo? I'd be curious to see the full video you pulled those screengrabs from. I think I'll buy the Meike lens and do the same thing. Can you update this thread if you try the Laowa 6mm?

[Ben Lalande]

Also, I wonder if this 3.5mm lens would vignette on super-16. Thoughts?

[Raymond Zrike]

Anything that covers micro 4/3 will cover super-16, so I would assume so (having not used the lens).

[Volker Bendt]

For Bolex you should also consider the Switar 10mm with Aspheron lens, which will give you 5,5mm without distortion.

No experience with the older Switar, but the preset series fully covers S-16even with the Aspheron.

Volker

[Ben Lalande]

@Raymond Zrike That lens does cover M43, but it's a circular fisheye. If you check out sample photos, you'll see that the image is a big round circle. What I'm wondering is how much of the circle and black edges we would see on a bolex s16. I'm assuming we'd see the black edges on the edges of the frame, but not sure.

[Allyn Iwatsuru]

On 10/4/2022 at 6:36 PM, Ben Lalande said:

Also, I wonder if this 3.5mm lens would vignette on super-16. Thoughts?

It will vignette, I can see a little bit of vignetting on the upper left and I’m shooting just regular 16. Another friend I showed how to make this has hard vignetting on the right.

[Ben Lalande]

Would you mind posting more samples, and potentially video samples if you can? I would also be really curious to see your friend's results with the hard vignetting...

[Marek Vesely]

On 10/5/2022 at 10:49 AM, Volker Bendt said:

For Bolex you should also consider the Switar 10mm with Aspheron lens, which will give you 5,5mm without distortion.

No experience with the older Switar, but the preset series fully covers S-16even with the Aspheron.

Volker

Not true at all. The 5.5mm Aspheron doesn't cover S16 at all. You need about 10% zoom to clear the vignette. And that's with the latest multicoted 10mm and Aspheron. 

[Daniel Meier]

Any chance of giving us a manual on how to build the adapter?

Or even better: did anyone figure out a 3D model yet?

I would love to have one if these Frankenstein-Adapters.