Mamiya G lenses for the Mamiya 6 rangefinder

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Rob de Loe
Rob de Loe Contributing Member • Posts: 907
Mamiya G lenses for the Mamiya 6 rangefinder
1

You never read about people adapting Mamiya G for the Mamiya 6 medium format (6x6) rangefinder to mirrorless cameras because there are no adapters. There are no adapters because the lenses have internal shutters that are shut when the lens is off the camera, and can only be opened from the camera. Recently Fotodiox made an adapter that lets you control lenses for the successor Mamiya 7 on a Fuji GFX, but the 6 and the 7 have different mounts, so the Mamiya G lenses continue to be used on Mamiya 6 rangefinders, and nowhere else.

Mamiya G 50/4 (left) and 150/4.5 (right)

These lenses have an excellent and well-deserved reputation among film photographers, and they still sell for a pretty penny. They're small and light (for medium format lenses), and cast a nice big image circle that covers 6x6 on 120/220 film.

I'm using the two you see in the picture on my Fuji GFX 50R. This was my most challenging lens adaptation project, so I thought I'd provide a quick write-up for other lunatics that want to try. Before I begin, I want to give a shout-out to Christoph Kuegler, a German photographer who led the way by converting his Mamiya 7 lenses for his Alpa camera. His example gave me the confidence to take this on. Another big thanks to my friend JG for his machining and other advice.

First, why bother? There are lots of other lenses that can be adapted much more easily to GFX cameras. The driver for me is I needed a light, high quality 45-50mm lens that allowed for 15mm of shift on my Toyo VX23D + GFX 50R digital view camera outfit. This is a bit of a dead zone. I use lots of Pentax medium format lenses, and the options in this range for 645 and 67 do not cut it. Large format and tech camera lenses less than 60mm normally have strong lens cast on shifting, and I didn't want to have to shoot a lens cast correction frame every single time.

The Mamiya G 50mm f/4 is a near-symmetrical lens, so I was taking a chance that it would have lens cast too; nonetheless, I figured it was worth the chance given the image quality of the files that Christoph shared with me from his adapted Mamiya 7 lenses.

In a nutshell, here's how the adaptation worked:

  • The shutter has to be locked open. This requires disassembly by an expert. Bill Rogers from Mamiya Repair did the work for me.
  • Once I got the lenses back from Bill, I had to replace the Mamiya 6 lens mount because there are no adapters. Olympus OM lens mounts are a fraction of a mm wider than the Mamiya 6 mount. I used the mount piece of junk Olympus OM 50/1.8 lenses (the ones with two-piece mounts). A bit of light sanding got them to the right diameter. The inside flanges had to be removed, and I had to make the screw holes that corresponded to the ones in the lenses. For the 50/4, I also had to create inside "pockets" for screw heads in the lens that stick out in the space where the lens mount sits.
  • I didn't want the electronic connections flapping around, so I snipped the cable and removed the end with the contacts.
  • Finally, the 150/4.5 had a light baffle that prevent veiling flare on the rear lens group. It didn't fit with the OM mount, so I installed a simple flocked tube over the lens group as a temporary measure. I'll replace the one you can see in the picture with a more durable one, but even this simple solution works perfectly.

Olympus OM lens mounts on Mamiya G lenses. Note the flocked tube around the rear lens group on the 150/4.5. It's essential to eliminate flare.

I adapted these lenses to use on my Toyo VX23D, a digital view camera. To mount them, I had to install an Olympus adapter on the back of a recessed Toyo lens board. This was relatively straightforward in comparison to the mount conversion. K&F Concept makes an OM to EOS adapter that fit nicely on the back of the Toyo board. Olympus OM lenses have the lens release in each lens, and that part doesn't fit on my converted Mamiya G lenses. The K&F Concept adapter has three strong springs that hold the lens tight. I can also lock the lenses in with a pin from the rear, but so far that hasn't proved necessary.

Toyo recessed lens board in my Toyo VX23D camera. The lens mount is a K&F Concept OM to EOS adapter that is screwed to the back of the board.

I rarely use my GFX 50R hand-held, but I'd like to have the option to use the Mamiya G 50/4 that way. The solution I'm currently putting together uses a GFX to M65 thread adapter, an M65 thread 17-31mm focusing helical, and another K&F Concept OM to EOS adapter screwed to the front of the helical. I can use the helical to set the flange distance, and then lock it down and use the lens normally.

Was it worth it? Without question, this gamble has paid off for me. These lenses are incredibly good performers. I wasn't planning to do a Mamiya G 150/4.5 because there are lots of other options that are easier to use, but the seller of the 50/4 had one so I bought them both. I'm glad I did. It's stellar from wide-open across the whole frame: sharp, contrasty, no CA whatsoever. Shift performance to 15mm is superb.

The 150/4.5 was a really nice bonus, but the big prize for me is the 50/4. It's not as good wide-open as the 150/4.5, but it's still very good. By f/8 it's simply outstanding across the frame -- again, sharp, contrasty, no CA, negligible distortion. And best of all, no lens cast, even when shifted 15mm on my GFX 50R. That shouldn't be the case because it's a near-symmetrical lens, but the back focus distance must be just long enough. Not having to shoot a lens cast correction frame and deal with the processing chore is a huge win for me.

Mamiya G 50mm f/4 mounted on its custom board on my Toyo VX23D

If you'd like to see some results for yourself, at the bottom of this page I put a link to a Google Drive that has full resolution JPEGs made with these lenses and others that I've tried or currently use on my VX23D + GFX outfit. https://www.robdeloephotography.com/Pages/Toyo-VX23D-and-Fuji-GFX-50R   These are infinity tests. Comparing the thirty-year old Mamiya G 50/4 to the modern Fuji GF 50/3.5 is instructive. The Fuji is a superb lens, but the old Mamiya doesn't embarrass itself -- and does better in some areas (notably purple fringing, which is distressingly strong on the GF lens and absent on the Mamiya). By f/8, which is the widest aperture I typically use, the image quality differences between the two lenses are not photographically significant as far as I'm concerned.

As a teaser, here's a 100% side-by-side of the Mamiya G 50/4 at f/4, and the Fujifilm GF 50/3.5 closed down to f/4. Remember, the Mamiya is wide-open. The only modifications to the file are a slight cooling of temperature on the Mamiya (they're quite warm), and a slight reduction in exposure on the Fuji (which tend to over-expose a bit). This is from the central part of the image.

Mamiya G 50/4 @f/4 (left) and Fujifilm GF 50/3.45 @f/4 (right). Enlarged to 100%

ProfHankD
ProfHankD Veteran Member • Posts: 7,602
Re: Mamiya G lenses for the Mamiya 6 rangefinder

Rob de Loe wrote:

You never read about people adapting Mamiya G for the Mamiya 6 medium format (6x6) rangefinder to mirrorless cameras because there are no adapters.

Ooh!  Another challenge!

In a nutshell, here's how the adaptation worked:

  • The shutter has to be locked open. This requires disassembly by an expert. Bill Rogers from Mamiya Repair did the work for me.

Ok. How does the shutter work? Is there a mechanical trigger or electrical? If electrical, are there interface specs anywhere?

 ProfHankD's gear list:ProfHankD's gear list
Canon PowerShot SX530 Olympus TG-860 Sony a7R II Canon EOS 5D Mark IV Sony a6500 +30 more
Rob de Loe
OP Rob de Loe Contributing Member • Posts: 907
Re: Mamiya G lenses for the Mamiya 6 rangefinder

ProfHankD wrote:

Rob de Loe wrote:

You never read about people adapting Mamiya G for the Mamiya 6 medium format (6x6) rangefinder to mirrorless cameras because there are no adapters.

Ooh! Another challenge!

I looked long and hard for the camera-side mount as a model, but I don't have the equipment or skill to fabricate a mount anyway. However, for someone who does it's probably a very simple project.

In a nutshell, here's how the adaptation worked:

  • The shutter has to be locked open. This requires disassembly by an expert. Bill Rogers from Mamiya Repair did the work for me.

Ok. How does the shutter work? Is there a mechanical trigger or electrical? If electrical, are there interface specs anywhere?

Electrical. Here's the unbutchered unmodified Mamiya G 50/4 from the rear. Note the electrical contacts at bottom.

Mamiya G 50mm f/4, unmodified, from rear

Here's an opened view of the Mamiya G 150/45. Each one is slightly different under the mount, but the arrangement is basically similar. Notice the ribbon cable that leads to those contacts.

Mamiya G 150mm f/4.5 with mount removed, showing ribbon cable and contacts

I believe the adapter that Fotodiox sells for Mamiya 7 lenses on GFX cameras is powered via the camera, in other words, you can only use it on the camera. It really does one thing: triggers the shutter to the open position and locks it open while shooting with the GFX.

If you want a look into the guts of a Mamiya 7 lens, here's the first in a three-part series of videos where the author opens up a Mamiya N 65mm lens to fix the broken flex cable. https://www.youtube.com/watch?v=U8WXoTxhGyM&t=383s

The Mamiya N lenses for the 7 have the basic DNA of the Mamiya G lenses I'm using. The mount is larger, and they cover 6x7. Some are almost exactly the same optics (e.g., the 150mm). From what I can see, the basics on the inside are quite similar.

ProfHankD
ProfHankD Veteran Member • Posts: 7,602
Re: Mamiya G lenses for the Mamiya 6 rangefinder

Rob de Loe wrote:

ProfHankD wrote:

Rob de Loe wrote:

You never read about people adapting Mamiya G for the Mamiya 6 medium format (6x6) rangefinder to mirrorless cameras because there are no adapters.

Ooh! Another challenge!

I looked long and hard for the camera-side mount as a model, but I don't have the equipment or skill to fabricate a mount anyway. However, for someone who does it's probably a very simple project.

That part would be easy enough for me.

In a nutshell, here's how the adaptation worked:

  • The shutter has to be locked open. This requires disassembly by an expert. Bill Rogers from Mamiya Repair did the work for me.

Ok. How does the shutter work? Is there a mechanical trigger or electrical? If electrical, are there interface specs anywhere?

The quick answer to my last question seems to be "no." That makes it not worthy of further effort for me... since I don't even own any Mamiya G lenses.  Oh well.

 ProfHankD's gear list:ProfHankD's gear list
Canon PowerShot SX530 Olympus TG-860 Sony a7R II Canon EOS 5D Mark IV Sony a6500 +30 more
Rob de Loe
OP Rob de Loe Contributing Member • Posts: 907
Re: Mamiya G lenses for the Mamiya 6 rangefinder

ProfHankD wrote:

Rob de Loe wrote:

ProfHankD wrote:

Rob de Loe wrote:

You never read about people adapting Mamiya G for the Mamiya 6 medium format (6x6) rangefinder to mirrorless cameras because there are no adapters.

Ooh! Another challenge!

I looked long and hard for the camera-side mount as a model, but I don't have the equipment or skill to fabricate a mount anyway. However, for someone who does it's probably a very simple project.

That part would be easy enough for me.

In a nutshell, here's how the adaptation worked:

  • The shutter has to be locked open. This requires disassembly by an expert. Bill Rogers from Mamiya Repair did the work for me.

Ok. How does the shutter work? Is there a mechanical trigger or electrical? If electrical, are there interface specs anywhere?

The quick answer to my last question seems to be "no." That makes it not worthy of further effort for me... since I don't even own any Mamiya G lenses. Oh well.

My use case is definitely quite niche... Someone who wants to shoot Mamiya rangefinder lenses on a GFX camera and doesn't need shift is much better off just getting the Fotodiox adapter and sticking with Mamiya N lenses for the Mamiya 7. One caveat though is the back focus distance of lenses like the 43mm and 50mm looks very short, so I would want to see samples on the sensor I'd be using to see if there's lens cast.

E Dinkla Senior Member • Posts: 2,245
Re: Mamiya G lenses for the Mamiya 6 rangefinder

Good approach, the Olympus mount is quite wide. A Canon EF mount even wider.

I thought that the Mamiya rangefinder lenses were worth it and conversion possible. In another thread on tilt/shift cameras I mentioned them and more: https://www.dpreview.com/forums/post/60056680

Met vriendelijke groet, Ernst
No photographer's gear list is complete without the printer mentioned !

Rob de Loe
OP Rob de Loe Contributing Member • Posts: 907
Re: Mamiya G lenses for the Mamiya 6 rangefinder

E Dinkla wrote:

Good approach, the Olympus mount is quite wide. A Canon EF mount even wider.

I thought that the Mamiya rangefinder lenses were worth it and conversion possible. In another thread on tilt/shift cameras I mentioned them and more: https://www.dpreview.com/forums/post/60056680

Met vriendelijke groet, Ernst
No photographer's gear list is complete without the printer mentioned !

A kindred spirit! I missed your post when I was researching this, Ernst, but I see we're on the same wavelength.

The choice of Olympus OM was really a matter of convenience: I had a junk OM 50/1.8 already, so it was easy to test fit. The Canon EF mount outer diameter is larger than the Mamiya 6 mount, so using a Canon EF to M42 adapter (of which I have several) was another option; it would have required more expensive machining to get it to the right diameter, so I went the easier route of OM.

Another option I explored was having someone fabricate a threaded mount in the correct dimensions. RAF Camera in Moscow could have done this easily and relatively inexpensively.

A final option I considered was a "Leitax" approach, in other words, fabricating a mount that sits on top of the existing Mamiya 6 mount and thus doesn't require modifications to the lens beyond the reversible work on the shutter that Bill Rogers did for me. I didn't go this route because the flange distance of Mamiya 6 lenses (56.65mm) put me right on the edge of what is usable on my Toyo VX23D. Putting a mount on top of the existing one would have made it very awkward to use tilt, whereas the OM mount part I used is thinner than the Mamiya G mount. On my setup, every mm counts.

E Dinkla Senior Member • Posts: 2,245
Re: Mamiya G lenses for the Mamiya 6 rangefinder

Rob de Loe wrote:

E Dinkla wrote:

Good approach, the Olympus mount is quite wide. A Canon EF mount even wider.

I thought that the Mamiya rangefinder lenses were worth it and conversion possible. In another thread on tilt/shift cameras I mentioned them and more: https://www.dpreview.com/forums/post/60056680

Met vriendelijke groet, Ernst
No photographer's gear list is complete without the printer mentioned !

A kindred spirit! I missed your post when I was researching this, Ernst, but I see we're on the same wavelength.

The choice of Olympus OM was really a matter of convenience: I had a junk OM 50/1.8 already, so it was easy to test fit. The Canon EF mount outer diameter is larger than the Mamiya 6 mount, so using a Canon EF to M42 adapter (of which I have several) was another option; it would have required more expensive machining to get it to the right diameter, so I went the easier route of OM.

The EF reverse rings have a wider opening. Either you shave off the filter thread part or integrate/glue them in a 3D printed part if the register distance difference allows it. On the other hand your Toyo boards may need a wider opening or with the front ring assembly of an EOS extension tube put at the front it might still fall within the total register distance of your tilt/shift camera assembly. I have no experience with conversions of medium format lenses though but use similar conversion methods for SLR lenses to EF mount.

Met vriendelijke groet, Ernst
No photographer's gear list is complete without the printer mentioned !

Rob de Loe
OP Rob de Loe Contributing Member • Posts: 907
What it can do: Mamiya G lenses for the Mamiya 6 rangefinder

This is what the lens can do:

Mamiya G 50mm f/4 +/- 15 shift

We won't get too excited about photograph because it's just a test shot... The point of focus is 4.28km (cell tower in the centre of the frame). The lens was shifted +/- 15mm at f/11 on a GFX 50R sensor. Even thought it's a near-symmetrical design for a medium format rangefinder (Mamiya 6), there was no lens cast I could see. Light falloff was strong enough to be bothersome so I shot LCC frames and tidied up with Flat Field Correction in Lightroom.

If you want to explore downtown Guelph, and see how the lens does, here's a link to a full resolution JPEG of this image: https://drive.google.com/file/d/1qbuac2ybk_mN517aJMKAd_Ow-Y7ak4_9/view?usp=sharing

AudiiDudii Contributing Member • Posts: 570
Re: What it can do: Mamiya G lenses for the Mamiya 6 rangefinder

One other significant benefit of using Mamiya 6 lenses with your Toyo setup is that the aperture rings aren't buried inside the recessed lens board the way they would be with most Pentax 645 lenses.

And while the being able to one lens board with multiple lenses won't save you a large amount of weight or bulk, every bit you do save will count double after you hike a few miles with a pack on your back!

Well done (especially the thinking-outside-the-box part of the process, which seems to be an increasingly rare occurrence in these days of copious consumer consumption)!

Rob de Loe
OP Rob de Loe Contributing Member • Posts: 907
Re: What it can do: Mamiya G lenses for the Mamiya 6 rangefinder

AudiiDudii wrote:

One other significant benefit of using Mamiya 6 lenses with your Toyo setup is that the aperture rings aren't buried inside the recessed lens board the way they would be with most Pentax 645 lenses.

And while the being able to one lens board with multiple lenses won't save you a large amount of weight or bulk, every bit you do save will count double after you hike a few miles with a pack on your back!

Well done (especially the thinking-outside-the-box part of the process, which seems to be an increasingly rare occurrence in these days of copious consumer consumption)!

Indeed that is a big plus. Using Pentax 645 lenses on my setup is awkward because of the rear-mounted ring.

Thanks kindly. Your various Frankencamera projects have been a real inspiration.

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