An optical mystery from adapted Mamiya N 43mm f/4.5 L lens

[Paul Spinnler]

13mm shift on a full-format sensor is roundabout what you'd get if you have a 90mm IC lens such as the 32 HR; the 43 XL has more shift reserves though and is very sharp also when shifted. This said, 13mm is not bad and good for many use cases. Would be cool if someone with a back could try one of these adapted M7 lenses.

As this adaptation requires "hard mechanical intervention" it hasn't been widely documented before the advent of live view-enabled tech cam setups - assuming Kugler is the pioneer - so it is very interesting to see that with the right mods these lenses can perform well on digital. Is there an avg. price for adapting these lenses?

These are really sharp shots. Let's not forget - 43 M7 is a 10-element Biogon design, ie more refined than the 8-element SWC variant which costs 16k in the Alpa mount courtesy of its rarity. The 43mm cost USD3k in 2001 which is the equivalent of USD5k today, ie the price shows how high end this lens was back in the day both in terms of constructive heritage and price point amid the rest of the MF lens offerings of that time.

 

[rdeloe]

Paul, this should give you a sense for what it would cost to find out if the lens is any good on a Phase Back:

• You need a nice copy of the lens; they are plentiful on eBay, used camera stores, buy and sell forums, etc. I got mine from a Japanese eBay seller (which is where I get most of my lenses).
• Someone has to dissassemble the lens, and then remove the bits that aren't needed, or get in the way (shutter blades, cocking arm, rear rangefinder cam assembly, circuit connectors). I highly, without reservation, recommend Bill Rogers from Mamiya Repair. His price was very reasonable for the skilled work he does. I'll let readers contact him for his cost, but to give you a sense, a single recessed Arca Swiss lens board cost me more than what his work to modify the lens cost. Note that if you had the misfortune to buy a lens with a stiff focus ring due to dried up grease, he can fix it too (not sure the cost). All three Mamiya N lenses I've purchased had smooth focus rings, and all three Mamiya G lenses had stiff ones.
• Once you get the lens back in your hands, you have to figure out how to attach it to your camera. As I explained above, I use the native Mamiya 7 mount and built an adapter board using a Mamiya 645 extension tube part. Arca Swiss knows how to do it now because they built one for Pierre following my instructions. If you don't want to get that fancy, four screws get the mount off and you can screw it to a board. If you can operate a drill press, you can do it yourself. SK Grimes in Rhode Island can do it easily. SK Grimes can build a mount too using my design. It's very simple.
• The last piece of the puzzle once you get the lens back from servicing is adjusting the spacing between the cells.* I'd ask Bill to sell you a 0.15mm spacer if he has one. My lens had the standard factory 0.5mm spacer. It stands to reason that if the lens you bought has the same 0.5mm spacer from the factory, then the same replacement spacer should work. I didn't have a nice spacer ring, so I just snipped a couple pieces off a 0.15mm spacer I did have that was the wrong size, inserted the pieces into the gap between the rear lens cell and the shutter, taped it over and tightened it down.
• If you're using it with a back, you don't have to remove the original cowl like I did. In fact, I recommend you don't remove the cowl because it's designed to protect the glass while not obscuring any part of the circle of good definition. My solution blocks part of the image circle, but it's the part I can't use anyway so I don't care.

If it proves to not be great on a Phase Back, someone with a setup like mine (or a Cambo Actus setup) might take it off your hands.

* On this step, it's what started this whole thread in the first place. It's entirely possible that this is a Fuji GFX 50R problem that will not happen on a Phase back. Christoph made the sample he shared with me on an IQ1 80. His sample was a flat stitch with 7.5mm of left and right shift. There's obvious colour cast (which looks very correctable). Image quality in the shifted area relative to the IQ1 80 sensor looked good. You'd have to ask him but he never mentioned having to adjust the spacing of the rear lens group.

 

[rdeloe]

Paul thought he saw some lens cast in those shift samples. I knew the 43mm was prone to this, but didn't think the G 50mm or N 65mm were. It's always good to check your assumptions... so I did.

These are f/11 LCC frames from shift tests for each of the three lenses. On the left is unshifted (0mm shift), and on the right is the noted shift. The images are made in mixed indirect daylight and overhead LED light.

It's very hard to distinguish colour cast from shadow in the unmodified images, so in the images you're seeing here I used +100 blue and +100 purple saturation to highlight any colour shift. In the unmodified versions of these images, it just looks like light falloff; there's no easily distinguished purple colour.

The takeaway for me:

• Lens cast is starting to show up even on 5mm of shift on the 43mm, but it's quite mild. Interestingly, I repeated the test this evening for the 43mm using just overhead light, and could not see any colour shift. I don't know why that is, but expect it has something to do with the light source.
• The 50mm is good shifted to around 12mm, but from 12mm to 15mm I should expect a bit of lens cast. This was a surprise, but good to know.
• The 65mm is clean to 15mm. No lens cast is present that I can detect or reveal with +100 blue and purple saturation.

 

[Focusrite]

These are f/11 LCC frames from shift tests for each of the three lenses. On the left is unshifted (0mm shift), and on the right is the noted shift. The images are made in mixed indirect daylight and overhead LED light

Curious as to whether there will be a repeat test of lens cast with the GFX100S? This thread has me rather fascinated with this lens, and I'm also certainly interested in whether the 100mp sensor may actually be the perfect (more affordable) digital back for shifting.

 

[rdeloe]

Curious as to whether there will be a repeat test of lens cast with the GFX100S? This thread has me rather fascinated with this lens, and I'm also certainly interested in whether the 100mp sensor may actually be the perfect (more affordable) digital back for shifting.

The news is good on lens cast. This is a 25mm shift of the Mamiya N 43mm f/4.5 L on GFX 100S (Left) and GFX 50R (Right). The bad news is you can only shift 25mm on a GFX camera if you're focused on something very close! At normal photographic distances, you're only getting 4-5mm in all directions.


That's a bummer for people who need more shift, but for me, this one is rapidly becoming my most used lens. I use it primarily for tilt and swing. Today I was out shooting and needed this entire length of concrete wall by the Speed River to be in focus. The Mamiya N 43mm f/4.5 L came through beautifully. The little bit of shift room was very handy for tidying up the composition after finding the correct swing angle.

 

[wallpaperviking]

The news is good on lens cast. This is a 25mm shift of the Mamiya N 43mm f/4.5 L on GFX 100S (Left) and GFX 50R (Right). The bad news is you can only shift 25mm on a GFX camera if you're focused on something very close! At normal photographic distances, you're only getting 4-5mm in all directions.

View attachment 203548
That's a bummer for people who need more shift, but for me, this one is rapidly becoming my most used lens. I use it primarily for tilt and swing. Today I was out shooting and needed this entire length of concrete wall by the Speed River to be in focus. The Mamiya N 43mm f/4.5 L came through beautifully. The little bit of shift room was very handy for tidying up the composition after finding the correct swing angle.View attachment 203549

Thanks for the update, very interesting indeed!

So, with the conversion you have done on your Mamiya 7 lenses, are you still able to control the aperture? Or is stuck at f11?

Also, with the 43mm lens, is the reason you are only getting 5mm of Shift due to the lens cavity of the GFX 100S?

How are you adapting the Mamiya lens directly onto your GFX 100S?

Thanks!

 

[rdeloe]

Thanks for the update, very interesting indeed!

So, with the conversion you have done on your Mamiya 7 lenses, are you still able to control the aperture? Or is stuck at f11?

Also, with the 43mm lens, is the reason you are only getting 5mm of Shift due to the lens cavity of the GFX 100S?

How are you adapting the Mamiya lens directly onto your GFX 100S?

Thanks!

On the Mamiya 6 and 7 lenses, the aperture is fully manual, so nothing had to be done to use it. The conversion I had done is necessary because the shutter in the lens is closed when the lens is off the camera. So you have to either lock the blades open, or remove them. Once converted, it's a fully manual lens with full control over the aperture. It's also no longer usable on Mamiya 6 and 7 cameras. You can get an adapter for Mamiya 7 unmodified lenses and GFX by the way (Fotodiox); there's no adapter for Mamiya 6 lenses.

I'm only getting 5 or so mm of shift with the 43mm because the rear end sticks out so far that it's inside the Rotafoot, and just about inside the GFX camera itself.

Here's a picture of the mount I built for direct adaptation of hacked Mamiya 7 lenses on GFX: https://www.getdpi.com/forum/index....-mamiya-n-43mm-f-4-5-l-lens.74265/post-881885 If you scroll down further in the thread you'll see the big rear end of the 43mm.

If you need wide(ish) and a lot more shift, the Mamiya G 50mm f/4 is great because it has a small rear end that doesn't clash with the Rotafoot. It's also optically excellent. You have to rip out the shutter, and you have to build a new mount. I wanted a bayonet mount on mine so I replaced the Mamiya 6 mount with parts from an Olympus OM mount. It pops on and off a custom board for my F-Universalis that has an OM mount (which I use with several other lenses). An even simpler solution is to bolt it directly to a lens plate for a Cambo Actus, or a lens board for an Arca-Swiss camera. That's easy-peasy for a machinist (e.g., SK Grimes in Rhode Island, who does this kind of work for photographers who can't do it for themselves).

Rob

 

[wallpaperviking]

On the Mamiya 6 and 7 lenses, the aperture is fully manual, so nothing had to be done to use it. The conversion I had done is necessary because the shutter in the lens is closed when the lens is off the camera. So you have to either lock the blades open, or remove them. Once converted, it's a fully manual lens with full control over the aperture. It's also no longer usable on Mamiya 6 and 7 cameras. You can get an adapter for Mamiya 7 unmodified lenses and GFX by the way (Fotodiox); there's no adapter for Mamiya 6 lenses.

I'm only getting 5 or so mm of shift with the 43mm because the rear end sticks out so far that it's inside the Rotafoot, and just about inside the GFX camera itself.

Here's a picture of the mount I built for direct adaptation of hacked Mamiya 7 lenses on GFX: https://www.getdpi.com/forum/index....-mamiya-n-43mm-f-4-5-l-lens.74265/post-881885 If you scroll down further in the thread you'll see the big rear end of the 43mm.

If you need wide(ish) and a lot more shift, the Mamiya G 50mm f/4 is great because it has a small rear end that doesn't clash with the Rotafoot. It's also optically excellent. You have to rip out the shutter, and you have to build a new mount. I wanted a bayonet mount on mine so I replaced the Mamiya 6 mount with parts from an Olympus OM mount. It pops on and off a custom board for my F-Universalis that has an OM mount (which I use with several other lenses). An even simpler solution is to bolt it directly to a lens plate for a Cambo Actus, or a lens board for an Arca-Swiss camera. That's easy-peasy for a machinist (e.g., SK Grimes in Rhode Island, who does this kind of work for photographers who can't do it for themselves).

Rob

Thanks Rob, much appreciated!

This could be a pretty lens if/when Hasselblad come out with a 100mpx BSI sensor..

 

[diggles]

An even simpler solution is to bolt it directly to a lens plate for a Cambo Actus, or a lens board for an Arca-Swiss camera. That's easy-peasy for a machinist (e.g., SK Grimes in Rhode Island, who does this kind of work for photographers who can't do it for themselves).

Congrats on the GFX100S Rob! I knew it was just a matter of time…

After seeing Rob's experiences with the Mamiya lenses I decided to try out the Mamiya 6 50mm and 75mm on the Actus with the GFX 100s. With Rob's help, we came to the conclusion that sending it to SK Grimes is my best option– I fall under the category of a photographer that has no experience modifying cameras and lenses. Like Rob, I sent both lenses to Bill Rodgers at Mamiya Repair to have the shutters removed.

Now the lenses are in the queue at SK Grimes. Each lens is going to be mounted to a Actus Copal 1 board. After seeing the lenses and boards, SK recommended making a mount adapter to go between the lens and board for "proper flush mounting and light lips". Otherwise the lens will be mounted on a rim around the bayonet mount that wasn't designed for that purpose. Anyway, I went with their recommendation. They are also making lens caps for the rear element. The rear of the 50mm sticks out enough that a cap can be placed directly on it, but the 75mm rear is recessed with no good surface for a cap so they are going to make an additional surface that the lens cap can secure against.

The lenses should be back in my hands in about 3 weeks.

 

[rdeloe]

Congrats on the GFX100S Rob! I knew it was just a matter of time…

After seeing Rob's experiences with the Mamiya lenses I decided to try out the Mamiya 6 50mm and 75mm on the Actus with the GFX 100s. With Rob's help, we came to the conclusion that sending it to SK Grimes is my best option– I fall under the category of a photographer that has no experience modifying cameras and lenses. Like Rob, I sent both lenses to Bill Rodgers at Mamiya Repair to have the shutters removed.

Now the lenses are in the queue at SK Grimes. Each lens is going to be mounted to a Actus Copal 1 board. After seeing the lenses and boards, SK recommended making a mount adapter to go between the lens and board for "proper flush mounting and light lips". Otherwise the lens will be mounted on a rim around the bayonet mount that wasn't designed for that purpose. Anyway, I went with their recommendation. They are also making lens caps for the rear element. The rear of the 50mm sticks out enough that a cap can be placed directly on it, but the 75mm rear is recessed with no good surface for a cap so they are going to make an additional surface that the lens cap can secure against.

The lenses should be back in my hands in about 3 weeks.

I was wondering how that project turned out Warren. I haven't used SK Grimes before but they have a good reputation. It sounds like they're on the ball. Fingers crossed you have good things to report when the lenses come back!

 

[richardman]

FYI, here's a lens diagram of the 43mm Mamiya lens, and it definitely looks like a Biogon

 

[buildbot]

FYI, here's a lens diagram of the 43mm Mamiya lens, and it definitely looks like a Biogon

View attachment 203583

One of the things Ken Rockwell got right haha, It's an improved 11 element biogon design, apparently.

 

[rdeloe]

I've been using it a lot lately. It's fast becoming my most used lens. I really like this focal length on a 33mm x 44mm sensor. Image quality leaves nothing to be desired. The GFX 100S deals very nicely with the lens cast (gone, effectively). It's a shame I can't shift it more on my setup, but tilt and swing are not limited (and that's what I use the most).