Horseman 6x9 Holder to Baby Crown Graphic (2x3)

Discussion in 'Camera Building, Repairs & Modification' started by Fragomeni, Oct 9, 2013.

  1. Fragomeni

    Fragomeni Subscriber

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    Hi all,

    I picked up a Horseman 8 exp 6x9 roll film holder for my 2x3 Crown Graphic. Unfortunately, it wasn't until after I made the purchase that I did the research to find that it isn't a perfect fit. I've seen this referenced on a few other pages but nothing that is giving me explicit information about where the mod need to be done for sure. This link includes a post (fifth post down, by Sebastian) that describes the issue as being because of the ridge along the left side of the Graflok back on the camera being too high. Can anyone confirm this? It seems that some others believed that the issue was with the grooves where the sliding locks fit. Apparently, if the ridge is actually the problem, then filing down the grooves will make the back appear to fit but the film plane will not be level.

    I'm wondering if anyone here has had personal experience modifying a Horseman back to fit a 2x3 Crown Graphic's graflok back? Lets please keep this on topic. I know that I can buy other backs. That's not the point. I'm interested in learning where the mismatch is between the camera and the Horseman back and what modification solves this. Thanks!
     
  2. Fragomeni

    Fragomeni Subscriber

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    Quick follow up. Just did a rough measurement here. There is indeed a difference in the depth (1.5mm) of the recess at the back of the holders. It seems that the theory about the ridge at the left side of the 2x3 Crown's graflok back may be accurate. It looks like the solution is to either grind down the ridge on the camera or grind down the recess on the holder. Can anyone confirm? See pictures below.

    horseman vs graflex.png crown graphic ridge.png
     
  3. Tom1956

    Tom1956 Inactive

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    It goes without saying I hope, that the first thing needed for something like this is a dial caliper. Whatever plan you might hatch to re-fit it, is where you are going to stand on your measurement distance from lensboard to film plane. That's all that really counts.
     
  4. Tom1956

    Tom1956 Inactive

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    Nevermind the face you're pointing at. Where it counts is the surface of a roll of scrap film to lensboard.
     
  5. Fragomeni

    Fragomeni Subscriber

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    Theres actually no concern for critical measurement here. The recess on the film holder is simply too shallow to accommodate the ridge on the Graflok back. To visualize this, stack two books on a table and the lay another book with one end atop the stacked books and the other end on the table. You get one end elevated preventing a flush mating of the face of the book and the table. Thats all thats happening here. Once that is corrected, it is the whole face of the film back that registers the film plane (which does match all other "graflok" back style roll film holders). This is simply an instance where the shallowness of the recess causes the left side of the film holder to be higher and not flush against the graflok back. Once the ridge is filed down, the holder will lay flush (if the theory is correct). The film plane would automatically register correctly once the mating is corrected.
     
  6. Tom1956

    Tom1956 Inactive

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    It's your camera to ruin. I don't say that to be trite, but to just say it's just not a plan. There is no plan. I would close the matter and find a regular Graflex roll film back. It's all that can be done. I've had to scrap unworkable ideas before too, sometimes with reluctance. But after I had put it out of my mind, something else will pop up.
     
  7. Fragomeni

    Fragomeni Subscriber

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    Thanks for the input Tom but like I said in the original post, what I'm looking for is simply confirmation one way or the other from someone who's done the mod. If I wanted to just buy another holder I would (and I still may) but this thread is about the particular mod I've brought up. (I opted for the Horseman because the Graflex holders are inferior with established film flatness issues. The Horseman is a superior back that I would like to use if the modification indeed solves the issue at hand.) You're absolutely right that the film plane is what matters so assuming that the film plane in the Horseman matches that of the Graflex, then the mod should work and that's what I'm asking about.

    So back on topic. If anyone has done this mod please chime in. Thanks!
     
  8. Tom1956

    Tom1956 Inactive

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    Understood. If no better answers do come along, I provide my meager input only to point out that assuming the 2 were identical measurements from face to film... The key work is assuming. Good luck.
     
  9. Fragomeni

    Fragomeni Subscriber

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    Understood as well. Upon confirmation, the Horseman backs are made to the same international Graflok back film plane registry standards of all graflok style backs. Interestingly, the "standard" isn't much of a standard and different backs from different manufactures, designed to be used interchangeably, actually turn out to have some variance in film plane registry. The variance is as much as 0.25mm from manufacturer to manufacturer. In most cases outside of extreme macro/micro work with extraordinarily thin DOF requiring absolute critical focus, a variance of 0.25mm is negligible and more than compensated for after stopping the lens down one or more stops. Also as a note, from the reports that I've seen, the variance in film flatness in the Graflex roll film holders is likely far more than the 0.25mm variance in the backs. In the end, I'm confident that the film plane will be fine for what I'm doing. Since we're on this, might as well post these measurements pulled from a since gone Medium Format forum and reposted on the LF forum for future reference in case anyone needs them (credit to Oren Grad for the numbers):

    Model Type / Formats / Depth
    Cambo slide-in / 6x4.5 / 4.95mm
    Cambo slide-in / 6x7, 6x9 / 4.95mm
    Cambo slide-in / 6x12 / 4.95mm
    Horseman clip-on / 6x7,6x9 / 4.95mm
    Horseman clip-on / 6x12 / 4.95mm
    Linhof S-Rollex clip-on / 6x7,6x9 / 4.85mm
    Linhof Rapid Rollex slide-in / 6x7 / 4.85mm
    Linhof Techno-Rollex clip-on / 6x12 / 4.85mm
    Sinar Zoom slide-in / 6x4.5 to 6x12 / 4.85mm
    Sinar standard slide-in / 6x7, 6x9 / 4.85mm
    Toyo clip-on / 6x7,6x9 / 5.05mm
    Wista clip-on / 6x7, 6x9 / 5.10mm
    Wista Type DX / slide-in 6x7, 6x9 / 5.10mm

    Now back to the regularly scheduled program. I'll likely just grind down the film back (not touching the camera) this weekend to see if the mod is as simple a fix as I suspect. Fingers crossed.
     
    Last edited by a moderator: Oct 9, 2013
  10. Prof_Pixel

    Prof_Pixel Member

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    Some time around 1960 Graflex added film flatness roller pins at each end of the opening; earlier roll backs without these pins have flatness problems.


    Edit: You also want to have a back with a flat-pressure-plate
     
    Last edited by a moderator: Oct 9, 2013
  11. Fragomeni

    Fragomeni Subscriber

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    Yep. I've seen that sited elsewhere as well. Apparently adding the pins improved film flatness substantially. Truthfully, I've used Graflex backs of all vintages and I've never really seen much of any issue at all with any of them. Granted, I stop down considerably for my work so shooting wide open may have shown more of an issue with some of the holders had I done that.
     
  12. Tom1956

    Tom1956 Inactive

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    All other things being acceptable, grinding or machining down on the edge of the film holdre would be the plan. At least it would be my plan too. Best plan I can think of. There aren't a lot of options otherwise, seems like. GL
     
  13. Fragomeni

    Fragomeni Subscriber

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    Yep, thats the only thing I can think of as well. Grinding down on the camera isn't an option for me. I'd rather ruin the back for the sake of experimentation. Ruining the camera, not so much.
     
  14. wombat2go

    wombat2go Subscriber

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    I can offer my experience from designing/building a metal camera to take the RH/10 which is standard on the 2 x 3 Crown. (see my apug thread)
    The top and bottom , and the left side you are referring to, were designed as light traps. The right side light trap is on the Graflex RH/10 rollfilm holder as a little ridge. If you try to grind the camera's left light trap off, not only will the camera be butchered, but, in my experience, unless you machine it flat to about 0.002 thou inch ( 0.050 mm) or less, and then add another light trap further out,, it will leak light.
    Also you might have to modify the clamps to press the Horseman tighter than the original design.

    For you comment about film flatness, I query what lens you are going to use?
    And how do you know it is perfectly sharp across a perfectly flat focal plane?
    Particularly, on wider apertures ( lower f/-) , I have pondered it is possible the original 90 ~ 105 mm lens designers might have been quite happy with a little bit of belly in the 6 x7 film plane. ( ??)
    And how is the lens going to be more parallel to the film, regardless of what better, "superior" back you use?

    Here is a measurement I took with vernier caliper of one old RH/10 holder on top/bottom of each pin roller [ inch] 0.206, 0.197, 0.202, 0.202.
    Let us assume my shaky hands and eyes got it right, what is there to do anyway with a "warp volume" of 0.005 inch ( 0.127 mm)
    Is it going to affect your ability to focus anyway?

    Have fun, but i ( as others above) hope you don't butcher your Crown for an ill advised reason you read on some internet crap !
     
  15. Fragomeni

    Fragomeni Subscriber

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    wombat2go, thanks for chiming in with input from your experiences. Like I said, I'm going to modify the holder.
    Regarding the lens and film flatness bits, this is my point. I don't care about slight variances here and there whether it be film flatness or the particular lens and how it projects across the plane of the film. All I care about is that it makes the pictures that I want. Nothing else matters. The question is simply will a slight modification to the roll film back provide a usable solution? I think the answer is yes and now I've got a nice little experiment to see if I'm right :smile:

    Ideas from anyone else? There must be someone here who's actually done this, no?
     
  16. Fragomeni

    Fragomeni Subscriber

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    To clarify, I know that I bought the holder because it is supposed to be superior to it's Graflex counterparts, but at this point this whole thing is just for the sake of experimentation. If it works that'll be great and if it doesn't thats totally cool too seeing as it'll be easy to pick up another holder that fits without modification and carry on without much concern :smile:
     
  17. Bob Eskridge

    Bob Eskridge Member

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    Well, I bought my Miniature Crown to use and DID carefully grind down the ridge on my Crown. It is hard to tell that the modification was done and now I can use my Horseman holder on it. Now I use Grafmatics, the RH12 Graflex back and the Horseman 6X9 backs. In fact I may try to put a Mamiya 4.5X6 back on it.

    By the way, the same requirement applies if you wish to use a Horseman back on a Mamiya Press or Universal with the G back.
     
  18. shutterfinger

    shutterfinger Subscriber

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    If you do not have a Digital Caliper ( http://www.amazon.com/s/ref=nb_sb_n...ix=digital+cal,aps&rh=i:aps,k:digital caliper ) get one. It makes camera work much easier.

    I too would modify the holder, not the camera, provided the holder has sufficient material and will not be weakened by the reduction in thickness. I do not currently have a 2x3 Crown to check how much could safely be removed from the back.

    Large Format Film Holder specifications, http://home.earthlink.net/~eahoo/page8/filmhold.html , for 2 x 3 is the front surface of the film is to be .197 inch from the edge of the holder ± .007 inch.

    I too have measured the backing plate on my Graphic roll film holders and found a similar variation as wombat2go but all distances are within film holder specs.
    Film flatness is only an issue when doing critical work such as architecture or close up/macro work. If you take a roll of film and run it through a Graphic RFH without pin rollers and one with pin rollers the film bows less at the center of the film gate on the holder with the pin rollers than it does in the one without the pin rollers.
    See http://www.graflex.org/helpboard/viewtopic.php?t=6391 for tips on Graphic/Graflex RFH problem solutions.
     
  19. Fragomeni

    Fragomeni Subscriber

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    Bob, thanks for chiming in with your experience. Interesting to hear that you've had success with this. My plan is to grind down the holder sometime this weekend. Should be a fairly quick job to take off 1.5mm.

    Shutterfinger, thanks for chiming in as well. Good to see confirmation of some of the numbers there.
     
  20. wombat2go

    wombat2go Subscriber

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    The 2 Graflex RH10's and the RH/8 here are all within about 0.197 +/- .003 inch
    The newest one, a Singer with the blue handles, is close to parallel on all 4 pin ends,to the limit of my calipers within 0.001 inch ( 25 micrometre)
    A 103 mm lens in 6 x7 at f/8 focussed close in (at 3 metre) can have a DOF of 350 mm which corresponds to +/- 0.25mm or +/- 0.010 inch of throw on the film plane.
    Boring numbers, but they put the accuracy of parallel film in perspective. The Singer back prices range from $80 to $100.

    The 2 x 3 Crown design actually is intended for the user to fine tune it using the front standard adjustments and the ground glass.
    The rails need to be dropped to the second click.
    For example-For mid to long distance work,
    For side to side sharpness, set each rail stop so that infinity focus is even, that no side ever goes beyond infinity.
    The lens can be tilted down slightly so when the tree-tops etc are at infinity, the foreground will always be on the sweet side.
    For example 1 degree, or 1 mm (0.025 inch) of down tilt on the lens board might be a good setting to bring the lower foreground slightly into the DOF.
    It is also possible to pre-set a small amount of front rise.

    Then lock all the adjustments, and just use the camera with the rangefinder.
    However the cameras won't fold up when set like that. I have an old video bag to carry them.

    For close up work,(and the bellows can extend out out to about 160mm) it is probably best to set the camera case- by case.

    The 2 x 3 Crown here is quite tight after the knurled screws are locked, except there is a little bit of flex in the lens tilt.
     
  21. erikg

    erikg Member

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    I know from my own experience that although the pins were an improvement there are still flatness issues with the Graflex backs. The Horsemen is superior. Stopping down won't help with architecture.

    Check this out: http://www.flickr.com/photos/egould/6979886059/

    Graflex roll film back with pins.
     
  22. Fragomeni

    Fragomeni Subscriber

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    Just wanted to pop back for a quick update. Very long week but I finally got a chance this evening to try out the modification. It ended up being a little more work than I'd planned for but only because I took off a little too much material from the holder and so I had to patch a hole with a little high strength epoxy. It's done now and it fits the camera like a glove. I tried to take off about 1.5mm of material but ended up taking off probably a little more than 2mm because I'm exhausted and wasn't really paying attention to where I drew the line. I repaired my error which was an easy job thanks to my favorite kneadable epoxy. When all the cutting was done I found that the holder fit but the two sliding locks were still getting stuck just a bit so I took them off and sanded their edges a little thinner (sharper) and that solved that. So, now the holder is a little uglier but a lot more useful. Thanks all for chiming in with your thoughts and input. Now I'm gonna go make some pictures :smile:
     
  23. phh

    phh Member

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    I'd like to share my part of the same experience. I found that my Hosreman 6x9 back has 3.69mm ridge height and the Century Graphic 23 got 3.93mm. Since only 0.24mm is hard to control by hand filing, I then file it down to 1.5mm and afterward put thin foam tap between the gap. Now it looks OK and I'll try to see if there's light leak to it. ;-)
     
  24. Old-N-Feeble

    Old-N-Feeble Subscriber

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    I didn't realize there were inconsistencies in Graflok backs and accessories. I thought everything was standardized. Something to keep in mind...