RB67 Lens on Large Format Camera

[Neil Poulsen]

Does anyone know of a convenient way to attach an RB67 lens to a large format camera? Specifically, I'm thinking of attaching one to a Sinar lensboard. I've seen adapters to attach them to various digital cameras. But, I've not seen anything that relates to a 4x5.

If there's nothing ready-made, is there something that could be fashioned. For example, if there's an adapter for a different camera, one could figure out how to use in with a Sinar board.

Etc.

?

 

[Dan Fromm]

Neil, I b'lieve that RB lenses' shutters are cocked by the body. Will this be a problem for you?

People have improvised boards that accept 35 mm SLR bodies by attaching an extension tube that fits the body to the board. There are extension tubes for the RB, but I think the shortest if 45 mm long. Since the RB's register is 112 mm this approach may be problematic with short lenses. I'm thinking more of vignetting than of y'r Sinar having too long minimum extension.

 

[nwilkins]

you can cock the shutter by hand but presumably you'd need to get your hand in there right before exposing the film (ie after composing the image on the GG). that could be a problem. I bet some clever person could figure out a way around that though. otherwise I think the coverage on those lenses is pretty good, though you probably would get vignetting with any movements (and maybe even at infinity with no movements?).

 

[Kevin Harding]

Cocking it by hand before removing the darkslide would work, but isn't the lens triggered by the body as well? I'm not sure how the lens would be triggered.

 

[wombat2go]

I was getting ready to do that, and even purchased a low cost teleconverter as a donor for the mount.
The difficulty is in charging the shutter.
I was thinking to machine a light tight external ring behind the mount with a lever to engage the pins on the lens.
It would be quite a job to get right I expect, without drawings.

In the meantime, the Takumar 6x7 Lenses on a Speed Graphic are a much simpler solution:
https://app.box.com/s/rte9vqs9ub91lfgiyx7cysqpo7a2d8r1
Machining the Graflex lens boards with the Pentax 6x7 mount is fairly straight-forward:
https://app.box.com/s/3o99vlqmz9myv3d71f2c

 

[nwilkins]

Cocking it by hand before removing the darkslide would work, but isn't the lens triggered by the body as well? I'm not sure how the lens would be triggered.

you could use the lens in mirror up mode to get around that

 

[Kevin Harding]

you could use the lens in mirror up mode to get around that

Ah okay. That doesn't require intervention from the body? I know it requires two "prongs" to trigger properly: one for the mirror, one for the shutter...

 

[wombat2go]

To charge the shutter, the 2 pins (looking at rear) have to be rotated acw fully up to the red dots
To fire the shutter , the little pin at 11 0'clock has to be depressed, then rotate the 2 pins fully cw.

To fire the shutter in mirror up selector, attach a cable, repeat the above, then press the cable button.
The 2 pins have to be fully cw to allow the cable actuation.

 

[Mainecoonmaniac]

I think it way too complex and the image circle may not cover your LF film. Sorry to be such a downer

 

[sir_mamiya]

I think it way too complex and the image circle may not cover your LF film. Sorry to be such a downer

Yeah. This is mad.

 

[wombat2go]

Yes Maine, I purchased one RB67 lens only with the intention to do it as a fun project.
Then I realized that the Mamiya RB67 bodies are available for cents in the dollar, so I purchased an old one and spent my time replacing its bellows etc.
Also an slr has adavantages for the medium format lenses.

 

[Mainecoonmaniac]

They're great lenses

Yes Maine, I purchased one RB67 lens only with the intention to do it as a fun project.
Then I realized that the Mamiya RB67 bodies are available for cents in the dollar, so I purchased an old one and spent my time replacing its bellows etc.
Also an slr has adavantages for the medium format lenses.

I've been shooting my Mamiya RZ for over 30 years and the lenses are great. I got an old data projector lens from the scrap pile with the intention of using it for LF. My problem is a lack of a shutter. I might make a Guillotine shutter out of black mat board. I love tinkering too.

 

[Maris]

From memory Erie Patsellis made a RB lens board for a large format camera by using the front standard of a junker RB67. The last email contact for Erie I have in my notes is: erie@ epatselliscreativeservices.com.

RB67 lenses can be (and have been) adapted to LF. My own experiments indicate the 37mm fisheye image just misses the far side of the 4x5 format, the 50mm and 360mm just miss the corners, and the 127mm covers easily.

 

[Kyle M.]

I no longer have my RB but I'm trying to remember. I know that when you rotate the Mirror up knob on the lens and screw in a cable release pushing the cable release releases the lens shutter. If you were to cock the lens, compose and focus, flip the mirror up knob and rotate the pins does the aperture close? Or does it stay open till you push the cable release then stop down the aperture, close the shutter, and fire?

 

[Bipin]

I presume you could make some sort of ring inside the 4x5's bellows that cocks the shutter and mechanically links to the outside:

Imagine that the blue area is the lens mount, which is of course static and attached directly to the white lensboard. The red ring is also static and attached to the lens board. (I'd suggest either precise MIG welds or some carefully drilled holes for screws). The yellow flanges, however, move along the tracks cut into the static red ring. These flanges interact with the two pins on the RB67 lens.

The outside ring behaves like any other leaf shutter, whereby it is cocked with a motion following its outer circumference. When this outer ring is turned, so too are the screws on either side of the ring. These screws attach to the yellow flanges inside, thus rotating them around the central axis and cocking the shutter.

Another option that probably involves less CNC, rather more scavenging for parts, would be to remove the elements and the shutter from the RB67 mount entirely. It would allow you to see if the native shutter could be cocked once it is removed from its housing, or perhaps if the elements screw into a standard #0 or #1 size.

Hopefully you find this helpful. Though it's only really a half-baked plan whipped up in 3dsMax a moment ago. Best of luck!

 

[M Carter]

I don't know about cocking the thing - but there are two different rear lens caps for RB lenses - one just pops on, and the other has tabs so you can bayonet lock the cap on. It wouldn't be the sturdiest thing ever, but it would get the lens mounted to a lot closer to the board than an extension tube would.

Then again, there are junker RB bodies on ebay for under fifty bucks, you could likely get the front standard off and rig up a trigeer.

But like everyone else here, I assume the image circle would be useless. With 4x5 lenses so cheap… yeah, I know - I'm the guy playing with getting a flipped Brownie Hawkeye lens on my RB with shift.

 

[MattKing]

The OP might be using a roll film back.

 

[pierre salomon]

Neil I worked on a similar project few years ago. The main thing is to find an old scrapped RB or RZ, proceed to remove the bellow and drill the two small trigger pins on the mount of the scrapped camera. Once done the lens will mount freely and the DOF preview button located on the bottom of the lens will allow you to choose your aperture. Mounting the RZ or RB front piece on a Sinar board is easy. My original idea was to create a poor man soft focus lens on F2 Sinar using my 150 SF RB or my 180 SF RZ with a cheap 2x Tokunar extender. I also used the Sinar shutter, the results were good but I could'nt shoot farther than 10 ft without vignetting. The close up results were great. I may have use some other lenses but when your clock past 60 years you could barely remember what you shot yesterday.. E mail me if you would like some pics.
Regards
Pierre

 

[Xmas]

The 140mm macro lens may have a larger image circle than the 127mm.

But using a 4x5 native lens bound to be cheaper and easier.

 

[Simon Benton]

The RB67 soft focus lens covers 4 x 5 - I used a junk RB67 front mount on a lensboard to use on my Rittreck View

 

[analoguey]

@OP

I had been exploring this idea when I first got my RB and 4x5 (and I had not bought an LF lens). I have seen (on the net) quite a few people do it, with explanations of what is needed to be done. No ready-made mounts, and what some of the posters above have listed as caveats vis-a-vis shutter cocking, etc., still hold.
Then I happened to see(and buy) an LF lens, and realised how *ridiculous* the idea was. (Not that it stopped me from contemplating or buying extension tubes to see if I wanted to pull the "lens mount" from there - I didn't though.)

Most LF lenses are ridiculously small v/s the RB lenses, which, by comparison are mammoths. Just the unnecessary strain on the camera body/lens mount from the weight of the lens, is not worth it, imho - especially as equivalent focal lengths are available at decent prices. One could still do it of course, and if you intend to, drop me a line, I'll see if I still have the links I had accumulated back then.

 

[Neil Poulsen]

Thanks for all the posts and excellent ideas. I think that finding a "for parts" body is reasonable in price and makes it fairly easy to attach.

 

[Ian Grant]

I think it way too complex and the image circle may not cover your LF film. Sorry to be such a downer

There are lenses for 35mm & 120 cameras that actually cover 5x4.

For instance the Schneider Tele-Xenar f5.5 360mm it was available in an M42 mount but it actually covers 7x5 and was mainly sold as such in a Compound #3 shutter. There's a Leitz Hektor sold in an M39 mount that covers 5x4 as well, you need to unscrew the lens head from the M39 barrel though. There' splenty of other similar lenses.

To Neil, you could use/modify a Mamiya rear lens cap.

Ian

 

[Neil Poulsen]

Thanks for all the posts and excellent ideas. I think that finding a "for parts" body is reasonable in price and makes it fairly easy to attach.

To extend this thread a little further, the idea is to mount a digital camera on the back with a Mamiya RB/RZ lens mounted on the front. There are plenty of adapters to mount digital cameras onto the rear of a 4x5, in this particular case a Sinar Norma.

Of course, the digital camera will have a shutter, so there's no need for the between the lens shutter in an RB lens. One solution would be to permanently tie open the depth of field preview lever on the RB lens using, say, a length of fishing line. One could then manually open the aperture for focus and manually close it down for the exposure. Apparently, the shutter needs to remain cocked, so as to attach and remove the lens from the mount.

There are also all the RZ lenses, and this raises a few questions:

> Are there any advantages of using an RZ lens over an RB, or vice versa?

> Can either an RZ or RB mount be used to mount either an RZ or RB lens? (I know that RB lenses can be attached to an RZ mount.)

> Do RZ lenses have the same kind of depth of preview lever as the RB lenses? Could the same solution anticipated above for RB lenses also work for RZ lenses?

> Aren't RZ lenses electronic in nature? Would this interfere with what I'm contemplating?

I don't know about cocking the thing - but there are two different rear lens caps for RB lenses - one just pops on, and the other has tabs so you can bayonet lock the cap on. It wouldn't be the sturdiest thing ever, but it would get the lens mounted to a lot closer to the board than an extension tube would.

Then again, there are junker RB bodies on ebay for under fifty bucks, you could likely get the front standard off and rig up a trigeer.

But like everyone else here, I assume the image circle would be useless. With 4x5 lenses so cheap… yeah, I know - I'm the guy playing with getting a flipped Brownie Hawkeye lens on my RB with shift.

Mounting the lens to a rear cap would certainly work for a while. But like you, I'd be concerned about the longevity. But, thanks for pointing out that these rear lens caps exist. It might come in handy as a short term solution.

And correct, extension tubes do indeed extend the lens a distance from the camera. That's a concern for being able to focus. One nice thing about the Sinar cameras, is that their minimum focus distance is under 40mm, including the Norma.

 

[epatsellis]

From memory Erie Patsellis made a RB lens board for a large format camera by using the front standard of a junker RB67. The last email contact for Erie I have in my notes is: erie@ epatselliscreativeservices.com.

RB67 lenses can be (and have been) adapted to LF. My own experiments indicate the 37mm fisheye image just misses the far side of the 4x5 format, the 50mm and 360mm just miss the corners, and the 127mm covers easily.

Indeed, it's been probably 8 to 10 years ago. I have a pdf somewhere documenting it, I'll find it and upload it to one of the online file sites and post the link for future reference .

Best contact method is either pm here or epatsellis@yahoo.com


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