Mounting a Mamiya MF 90mm on a Toyo 45G?

<p>Hi,<br>

I would like to mount a 90mm lens for the Mamiya RB67 on my Toyo 45G. I have modified the Toyo to mount a DSLR to the back standard. (See .) Unfortunately, there is not enough clearance between the Schneider 90mm and the DSLR mount for me to focus at infinity. The Mamiya 90mm would work because its asymmetrical design creates a longer distance between its flange to focal plane when focusing at infinity (112mm).<br>

Does anyone have any advice on how best to mount the Mamiya lens on a Toyo lens board?<br>

Thank you in advance.</p>

<p>You could remove the elements and mount in a Copal 1 shutter. I have done this with a Bronica 150 lens whose elements fit a Copal 0 shutter.</p>

<p>John,<br>

Thanks for the suggestion. I am now looking into dismantling a RB67 lens. Did find a couple of very useful links, which I am listing below for those who might be interested.<br>

I do have another question for you and others. I do not need a shutter because the DSLR has its own. However, aperture control could be useful.<br>

If I don't use a Copal or other shutter, is there a way to properly space the front and rear lens cones?<br>

General discussion on dismantling a MF Mamiya lens:<br>

http://www.kyphoto.com/classics/forum/messages/6900/4174.html?1134694877<br>

Very useful set of photos of how to disassemble a Mamiya RB67/RZ67 lens<br>

http://logojoe.com/RB-RZ/lens-shutter/index.htm<br>

Also, if I do not disassemble the lens (since I also use it on my RB67), does anyone have any suggestion on how to mount the intact lens on a Toyo lens board?</p>

<p><a href="http://www.openphotographyforums.com/forums/member.php?u=2897" >Erie Patsellis</a> has done this, and has a photo of his setup in this thread:<br>

http://www.openphotographyforums.com/forums/showthread.php?t=5757<br>

Unfortunately, he references his website which seems to be down and I've been unsuccessful at finding any more information. I think he took the front of a broken rb67 and mounted it to a toyo lensboard, but I'm not sure how he got cocking the shutter to work. Please post any results you find - I think this would be a fun project, so I'll be looking forward to seeing if you're any more successful at finding this info that I've been.</p>

<p>Eric,<br>

Thank you for the link to the thread containing Erie Patsellis' RB67/45G hybrid. Fantastic, and it would be something I would want to replicate. I have emailed him to ask for any advice or suggestions, and to post the photo of his hybrid. I will have to look for a used Mamiya RB67 body, preferably one that is not functional and cheap because all I want is the front for the lens mount. I will mount my DSLR to the back standard, and I already have a home-made adapter for that. So, I guess I will have a RB67/45G/DSLR hybrid.<br>

I did bid on a mount on ebay but did not get it. Below is a photo of that mount.</p>

<p> </p><div></div>

<p>That looks interesting... it doesn't seem like it can cock the shutter, do you know? I suppose with the dslr hybrid, since you'd be using the body's shutter you could just lock dof preview to close down to the selected aperture. With Erie's setup, I'll be curious when he gives more details... I'm wondering how he focuses, and whether he was able to fashion a ground glass to swap with the rb back - I wonder if you can just use a gg from something like a crown graphic 23? With your dslr hybrid, have you found dust on the sensor to be a problem at all? It seems like exposing to the relative cavern of the 4x5 body for any kind of long exposure would necessitate frequent cleaning?</p>

<p>Paul, I've not gotten your email, you can email me at erie at shelbyvilledesign dot com.Due to my not paying attention to when my domain was expiring, I lost the domain and some squatter seems to think that several hundred dollars is a fair price for a domain that is my first and last name. Bollocks, as they say in England. After this semester is done, I'll be moving the files to shelbyvilledesign.com, I'll post when I get them moved.<br>

to answer Eric's questions:<br>

Focusing is done with a piece of ground glass epoxied to the film rails of a junk back with everything but the front piece removed. You have to add 2 small screws to engage the slide lock/darkslide interlocks. I mounted an RB revolving back onto the rear of the 45F (not a G, the only difference being geared shift, I have a Sinar P, so it doesnt' make sense for me), so you can shoot horizontally or vertically. If you remove a revolving back it should be ridiculously obvious how to mount it, If it isn't, question your ability to do any mods.<br>

Cocking the lens is trivial, if you remove the entire front standard from an RB, not just the (seemingly butchered) ring as above. There is a shaft at the bottom of the front standard that rotates 180 degrees or so to cock the shutter, mount a lever, make a gear train, whatever floats your boat.<br>

I use both RB lenses and LF lenses with either 6x7 backs or 4x5 sheet film. I built this originally with the expectation of buying a 37mm fisheye, but prices have gotten silly on them again, I'm a full time student and $800 or $900 is way out of my budget.<br>

Paul, don't wast your money on that mount or one like it, buy an AS-IS RB from KEH and for just a few dollars, you'll have everything you need to build a mount that will actually work properly.</p>

<p>Eric,<br>

Erie has been kind enough to answer many of your questions. As for my DSLR/Toyo hybrid, yes dust is a problem. I have an old Nikon D70 that I use for all of my experiments (pinhole photography, camera fling, attaching to 4x5, etc.). It has about 30k clicks on it and is suffering from memory card errors now and then. So, not a big lose if it is damaged. I think my next step is to put a filter on my adapter, which should be easy.<br>

Erie,<br>

Thank you very much for your response. I look forward to your new website. There are copies of the photo of the RB45/LF hybrid on the web, which I downloaded. Happy to post it here for others to see with your permission. I agree with you about following your approach. As I mentioned, I have a RB67, but I want to keep for its intended use as a MF camera. I have been hunting for a cheap RB67 on ebay and craigslist. If that fails, then KEH.<br>

Interesting that you did not get an email from me. I sent it via photo.net. Perhaps this site does not have you most current email address. But, I also have problems sending emails to others using photo.net.<br>

Everyone,<br>

Will keep you updated but not likely to do much until next year. The holidays are upon us, and I have many family (and fun) obligations. Happy holidays to all.</p>

<p>Paul,<br>

I have a Tele-Xenar 1:5.5 / 240 in a barrel mount with aperture from 5.5 (i.e. fully open) to 32. It is a shutter size 1 like your Seiko. Depending on how large the rear of each element is - the part that would screw into the shutter/barrel may fit. If you want to try, contact me and I will send the barrel to you. Cheers, John.</p>

<p>John,<br /> <br /> Yes, I would be interested in the lens barrel. Not sure if it will work for the Mamiya, but I am willing to try. I emailed you via photo.net, so I hope you got my message. <br>

Also, thanks for the information about the Seiko shutter in the Mamiya lens. That is useufl information.<br>

Thanks.</p>

<p>Sorry to highjack the thread, but I have a question with this. Will an RB lens cover 6x9? Anybody know. As I would like to use my 6x9 back with an RB 50mm lens.</p>

<p>Thanks.</p>

<p>Darcy</p>

<p>50mm, maybe. How critical is corner sharpness? since the RB is really an 8x8 camera, the 50 should cover 6x9. <br>

Honestly, with movements my need for really wide lenses is far less, I don't think I've used my 50 or 65 in several months. Lenses from 90mm+ cover 4x5 with a little wiggle room.</p>

<p><em>since the RB is really an 8x8 camera</em><br>

<em></em><br>

Mmm . . . not sure about this. I have heard of 6 x 8 backs for Mamiya, but 8 x 8 would need more image circle, and I don't think you can infer the lenses are designed to reach out that far. FWIW, the Graphic '23' backs, which are the ancestors of the RB backs, were also close to 6 x 8.</p>

<p><em>90mm+ cover 4x5 with a little wiggle room.</em></p>

<p>Well, as they say in Missouri. The normal lenses for RB are presumably Gausses, and I suspect it is impossible for a 90mm or 127mm Gauss lens to cover 4 x 5 adequately. But I'm open to being convinced by the evidence. I bet you are getting illumination of the corners, but falling well short of good resolution.</p>

<p> No disagreement about the resolution, it can work for some subjects and is horrid for others.</p>

I would use the 50mm lens for landscapes. So not as crucial but I would prefer edge to edge sharpness.

<p>Actually an RB67 lens must cover 8x8 if you consider that its 6x8 back can be rotated 90 degrees.</p>

<p>Thanks for the comments on the 50mm. I am considering purchasing either the Mamiya RB67 50mm or 65mm. For my purpose, 8x8 or even 7x7 would be more than adequate coverage. Any opinions on which is better in terms of resolution, color and contrast?</p>

<p><em>Actually an RB67 lens must cover 8x8 if you consider that its 6x8 back can be rotated 90 degrees.</em><br>

<em></em><br>

Not so. Think about it for a minute and you'll see why. Or just calculate the sizes of the required image circles.</p>

<p><em>There is a shaft at the bottom of the front standard that rotates 180 degrees or so to cock the shutter, mount a lever, make a gear train, whatever floats your boat.<br /> </em><br>

Erie, when I rotate the focus knob and move the front standard forward, I can see the shaft you are speaking of. Cocking the shutter rotates it one way, and releasing it, the shaft reverses. Thanks for the tip. I'm curious, however, how the lever or gear train would be mounted - if it would be inside of the lens board or outside? Also, the shutter mechanism presses a small round metal pin on the back of the lens to release a mechanism that allows that shaft to rotate - how do you get around all of this?<br>

Many thanks! This is surely going to be an exciting project.<br>

_S</p>

<p>Darcy, I was thinking the same thing about a spare 50mm Bronica GS-1 lens I have. I will mount the elements in a Copal 0 shutter. Since it is a retrofocus design like the Mamiya, there should be enough of a back focus to make for a reasonable distance from the film/digital plane of a LF camera. The new Linhof Techno would be great for this - I must sell a great deal of photographic "stuff" in order for this to happen though.</p>

<p>This thread is old, I know, but I'm planning on mounting an RZ lens to a lens board by simply using a lens cap with a hold drilled in it for the light to pass through. Simple enough, and plenty sturdy. The downside is that RZ lenses have a built in shutter controlled electronically, and the aperture is wide open all the time. As a quick and dirty method of allowing for aperture adjustment, I'm planning on keeping the depth of field preview lever pulled all the way over. I'll secure it with... dental floss. Pretty ghetto, I know, but it works. If I come up with a better idea, I'll implement it, but that's what I'm doing for now. The other alternative would be to pay $400+ for a Cambo adapter. I prefer suffering the indignity of knowing my contraption is plastic and dental floss (for now), because if it works, it works.<br>

The only reason I'm doing this at all is because A) I already own RZ lenses, and B) I'll be using a 35mm camera as my digital back. This combination should allow quite a bit of movement on the view camera relative to the sensor size.</p>

<p>Wow, guess I need to keep up with these threads.</p>

<p>Steve, with a lens mounted, the only thing you need to do is rotate the shutter cocking lever to cock the lens and compose, with the lens in MLU mode, rotate the lever as if the body was firing the lens, it will close the shutter, stop down and wait for you to fire the shutter with the lens mounted release, it's really that simple.<br>

John, there are plenty of LF scan backs out there, they often come up used, unless you have a MFDB and you want to play, that is. Personally, I think that anything from Linhof is excellent, but very, very expensive. You would be better served using a P or even a toyo before committing that kind of money. In fact, I'd save the lens, unless it is a direct fit into a copal 0 and find a used 47 f8 super angulon myself.<br>

Paul, I would avoid the RZ lenses, to each his own I guess. (KEH has used RB lenses ridiculously cheap these days, btw) Better than a lens cap, buy an AS-IS body, or an extension tube and steal the mount, or better yet, one of the uber cheap 2x rokunon converters. Using a 35mm digicam sounds good in theory, but the reality is far different. Expect weird color shifts if your camera has a microlensed sensor as well as significant limits on movements with shorter lenses (draw a cross section and you'll realize why).</p>

<p> </p>

<p>I am planning to use a Toyo in a similar experiment, I wonder if there is any gotchas or somethings I should be aware of? I have bid and won the Toyo, but yet to receive it.</p>

<p>Here's my RZ 110/2.8 mounted in a shutter. Not sure of the coverage because I don't have a 4x5 camera anymore... I'll test the infinity coverage with a piece of paper at some point.<br>

<img src="http://www.getdpi.com/forum/attachments/medium-format-systems-digital-backs/83892d1413957181-new-frankenlens-my-alpa-mam110.jpg" alt="" width="366" height="366" /></p>