Horseman 6x9 Holder to Baby Crown Graphic (2x3)
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!
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.
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.
Nevermind the face you're pointing at. Where it counts is the surface of a roll of scrap film to lensboard.
Originally Posted by Fragomeni
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.
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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.
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!
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.
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 Fragomeni; 10-09-2013 at 10:44 PM. Click to view previous post history.
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.
Originally Posted by Fragomeni
Edit: You also want to have a back with a flat-pressure-plate
Last edited by Prof_Pixel; 10-09-2013 at 10:59 PM. Click to view previous post history.