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Thread: Building a ULF adapter back for a smaller format camera: pros and cons?

  1. #1

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    Building a ULF adapter back for a smaller format camera: pros and cons?

    I own a 5x7 camera, a Rittreck View. I would like to go to a larger format, and know that an 8x10 adapter back was made for my camera. But I wonder about making my own, larger adapter back, possibly an 11x14. I realize that the camera has limited bellows draw (14.5 inches with my Pacemaker Speed Graphic lens board adapter on the front). But the adapter would add inches to the length, just in order to allow the light cone to cover the 11x14 format, and I could make it even longer. I know I would still be quite limited in both the lenses I could sensibly use, and would have limited movements. But am I missing some other limitation that is obvious to others with more knowledge than me?

    I made the 5x7 back for my Rittreck, and know I could make this 11x14 adapter, too. Building an entire camera might be possible for me, but beyond my budget. And the thought of making the bellows scares me.

  2. #2
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    Re: Building a ULF adapter back for a smaller format camera: pros and cons?

    FWIW, I've owned a Rittreck kit including the whole plate and 6x10 expansion backs.

    Jumping up two sizes is really a stretch for an expansion back. You'll need to sketch out the design and do some trigonometry to figure out whether it's even possible to make a configuration with a lens that will mount on the front of the camera that will allow focus without image cutoff. Even then, it will be at best clumsy and very limited.

    If you want to experiment with ULF on an extremely tight budget, you might be better off exploring simpler approaches like nested-sliding-box designs.

    EDIT: Perhaps this article from the LF Home Page will give you some ideas:

    The "cigar-box" handheld 11x14 camera

  3. #3

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    Re: Building a ULF adapter back for a smaller format camera: pros and cons?

    The bigger back you add to your back standard the more weight you add to it. Will its mechanics hold that added weight comfortably?

  4. #4

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    Re: Building a ULF adapter back for a smaller format camera: pros and cons?

    Oren Grad: Thanks for the link. From my reading of it, that design is not very appealing (to me) for a complete camera, though I'll keep thinking on it. It might lead to an even more 'Franken-camera' design. If I had an already-made 11x14 back, the decision on what to do would be much easier.

    As for figuring out whether it's possible, I can do that. I've made more than half a dozen telescopes and needed to figure out the baffles needed for contrast in refractors, and tube diameter/length for reflectors. And my sixteen-year-old son is a math wizard. Even without those helpful advantages, I have the camera already, and a lens that will cover the format (a 300mm Symmar), and another on the way (a 19-inch Apochromat Artar). It should be fairly easy to set up a test bed using the lenses, the camera, a dark cloth, and a sheet of glass or other reflective material, to check the possibilities. Or, again, am I not understanding some key limitation?

    Pfsor: My experience with telescope-making has also included finding ways/materials to limit weight. I have on hand some very thin, but very strong 1.5mm thick plywood. Used as sheathing on a hardwood or aluminum frame, it would be very light. I used it on this 14-inch reflector. The scope is over five feet long, and has a circumference of 56 inches, but the plywood added less than five pounds to the weight. The Rittreck seems plenty robust enough to support something that big, though of course the ground glass and film backs add a lot of weight. You may have hit on the limitation that kills the idea.

    Click image for larger version. 

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    I know this would be an unwieldy, even ugly, thing. The Rittrack view has a hole in its rear standard that is 7.25 inches on a side. On another forum, someone with an 8x10 back for the Rittreck wrote, 'The problem with the 8x10 back is this: wide angle limitation of about 180mm because of the bellows and about 400mm on the long side it will vignette because of the 5x7 hole'. The photo below shows the camera with an 8x10 adapter. My idea would add at least a few more inches, so I'd never use anything like a 180mm lens. 280mm might be a guess as to the short end, but that would be plenty (something like a 100mm lens on a 4x5 camera). If 400mm truly is the longest lens possible, then this project might not be worth pursuing, since about 450mm would be 'normal'. I am not a math wizard, though, so could someone offer any ideas about whether my idea would make this vignetting worse, or better, or have no effect? Or maybe the writer was mistaken? I could, of course, wait until the 19-inch (480mm) lens arrives, and just check through the test set-up I described. But it will be a week or so before it gets here, and this idea is itchy, and I want to keep scratching it.

    I could also make some sketches, or get my son to think it over. But my concern is that I might be missing something obvious that one of the ULF folks might see right off, and my son is busy with never-ending homework, learning some songs for a barbershop performance, and practicing some other songs on his bass (a bit from Jim Croce's 'Operator' has him stumped). He's a renaissance boy!

    Click image for larger version. 

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  5. #5

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    Re: Building a ULF adapter back for a smaller format camera: pros and cons?

    Here's a place that sells bellows. They might have 11x14" and they might do custom work:

    http://stores.ebay.com/ecbuyonline20...p2047675.l2563

  6. #6
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    Re: Building a ULF adapter back for a smaller format camera: pros and cons?

    The issue with hanging all that extra weight that far off the Rittreck's rear standard isn't so much the general robustness of the standard, but whether the retaining clips on the camera or the corresponding clips or pins on the cone can handle it without breaking or giving way. You can ease the geometry problem by going with a longer FL lens and correspondingly longer cone, but that will exacerbate the weight/lever arm problem. Alternatively, you can use a very short FL lens, extend the Rittreck as little as possible and get most of your extension from the cone, but then you may end up with the camera bed in your picture.

    You really should make some sketches, with the envisioned cone rendered at proper scale relative to the key dimensions (including bellows extension) of the camera body for a given focal length. Just by eyeballing the relationship between the cone defined by the camera and that defined by the add-on back, you should be able to calibrate your intuitions a bit and define the range of possibility even before you try to do any precise calculations.

  7. #7

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    Re: Building a ULF adapter back for a smaller format camera: pros and cons?

    xkaes: I had new bellows made for the Rittreck by 'tokyophoto' on eBay. They were fantastic to deal with, and if I recall correctly, will make custom bellows. If I were to build an entire camera, and wanted custom bellows, I would approach them first. Before that, though, I would look for used bellows around which to build the camera, I think. There are a couple on eBay right now that I might consider, if I had ready funds and was further along with my thinking. One set is more than 40 inches long, and has a front opening 12x18 inches and a rear opening 20x24. Overkill for me, but inexpensive. Another auction is for the main bits of a 14x17 inch x-ray machine, including the bellows. I won't link to them since this post will last far longer than those auctions. But even before looking for bellows, I would look for a beat up old 8x10 camera to modify. Skipping two step in size might be looking doubtful. One step would be much more sensible.

    But money is the big issue. And I may already have most of what I need to try the project with the Rittreck (I never throw building materials away!), other than film holders and film. I'd love to avoid making the actual 11x14 back, but could do so if I needed to, once I get a film holder to work from.

    Oren Grad: Thanks for more food for thought! I will make sketches.

  8. #8

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    Re: Building a ULF adapter back for a smaller format camera: pros and cons?

    Quote Originally Posted by Paul Kinzer View Post

    As for figuring out whether it's possible, I can do that. I've made more than half a dozen telescopes and needed to figure out the baffles needed for contrast in refractors, and tube diameter/length for reflectors. And my sixteen-year-old son is a math wizard. Even without those helpful advantages, I have the camera already, and a lens that will cover the format (a 300mm Symmar), and another on the way (a 19-inch Apochromat Artar). It should be fairly easy to set up a test bed using the lenses, the camera, a dark cloth, and a sheet of glass or other reflective material, to check the possibilities. Or, again, am I not understanding some key limitation?

    Pfsor: My experience with telescope-making has also included finding ways/materials to limit weight. I have on hand some very thin, but very strong 1.5mm thick plywood. Used as sheathing on a hardwood or aluminum frame, it would be very light. I used it on this 14-inch reflector. The scope is over five feet long, and has a circumference of 56 inches, but the plywood added less than five pounds to the weight. The Rittreck seems plenty robust enough to support something that big, though of course the ground glass and film backs add a lot of weight. You may have hit on the limitation that kills the idea.



    I am not a math wizard, though, so could someone offer any ideas about whether my idea would make this vignetting worse, or better, or have no effect? Or maybe the writer was mistaken? I could, of course, wait until the 19-inch (480mm) lens arrives, and just check through the test set-up I described. But it will be a week or so before it gets here, and this idea is itchy, and I want to keep scratching it.

    I could also make some sketches, or get my son to think it over. But my concern is that I might be missing something obvious that one of the ULF folks might see right off, and my son is busy with never-ending homework, learning some songs for a barbershop performance, and practicing some other songs on his bass (a bit from Jim Croce's 'Operator' has him stumped). He's a renaissance boy!
    Sorry Paul, but I just don't buy it. On one hand you say how great you're to build telescopes - and on the other hand you don't even know that starting with a sketch would answer the fundamental questions about feasibility of the project? And you don't know how to make the sketch and it must be your son who can make it but he cannot....
    I don't buy it. I'm out. Sorry.

  9. #9

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    Re: Building a ULF adapter back for a smaller format camera: pros and cons?

    Pfsor: I'm truly sorry that you feel that way (really, it makes me feel rotten).

    But, actually, I think you've mis-read me. I did not say I was 'great' at making telescopes, just that I had. And I made plenty of mistakes along the way. Nor did I say that I 'did not know' that making sketches would answer fundamental questions; nor that I 'don't know how to make' them (of course, I made lots of sketches for my telescopes!); nor that it's my 'son who can make it' (I brought up my son's math skills in response to Oren Grad's statement that I'll need to 'do some trigonometry to figure out whether it's even possible to make a configuration with a lens that will mount on the front of the camera that will allow focus without image cutoff'). In fact, in another post before yours here, I wrote that I will make them for this project; and I have now done some very rough ones, just to get a picture of what it might look like (though I may have made mistakes in them, because of my lack of knowledge). But if someone had shot my idea down immediately, then making sketches would have been a waste of time. That's why I made my post.

    I've written this post because I had an idea. I'm the first to admit that lots of my ideas are bad. I hoped to get opinions from others with lots more understanding and experience than me, to help me avoid obvious (to others, anyway) mistakes; maybe even a response form someone who had attempted the very thing I was contemplating (that would still be nice). I'm also, I admit, both curious and impatient. Maybe I should just have done more work first, before posting. Still, I've already gotten some helpful advice, and been given ideas about where to go from here.

    Again, my apologies. I could take offense at your 'not buying it', which implies I'm lying or... something. But for all you know, I could be. So, I'll leave it at that.

  10. #10

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    Re: Building a ULF adapter back for a smaller format camera: pros and cons?

    Paul, you don't need trig to find out whether a barrier behind a lens will cause mechanical vignetting. A simple similar triangles model will do.

    Let the barrier be db behind the lens and hb high. Let the film plane be df behind the lens and hf high. If hb/db < hf/df, trouble. Draw the triangles.

    Where in the lens the distances to barrier and film plane are measured is an interesting question. Fortunately for most lenses whether the starting point is the lens' rear node (close to the diaphragm) or the vertex of the rear element makes little difference.

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