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Photo Forum / Film Photography / Medium format / March 2004Distance between leading edges
Hi! The other night I had this crazy idea of making my own back for the 120. The idea is to make it versatile so that I can do some creative experimentation with it without breaking my budget or other cameras. One of the first obstacles is the film transfer mechanism. Ideally I would like to switch between framesizes (645, 6x6, 6x7, 6x8, 6x9, 6x12, 6x17). The last two will probably need a separate back though. The distance between the leading edges of the images on the film is problematic. My eyeball examination would give 48mm for the 645, 64mm for the 6x6, and 93mm for the 6x9 (in metrics as are the framesizes). Are these correct? How about the other formats? Are the standardised somewhere? And the big question: how to keep them even when the film is winding around the spool? Any info/ideas appreciated. Jack > Hi! > [quoted text clipped - 10 lines] > question: how to keep them even when the film is winding around the > spool? Any info/ideas appreciated. Sinar makes a multi-format back called the 'Zoom'. Might be worth trying to get a look at one to see how their mechanism works - it's probably possible to hire them. Peter > eyeball examination would give 48mm for the 645, 64mm for the 6x6, and > 93mm for the 6x9 (in metrics as are the framesizes). Are these correct? > How about the other formats? Are the standardised somewhere? And the big Only standard are what you want. Different companies tend to have a habit of being a little different. > question: how to keep them even when the film is winding around the > spool? Any info/ideas appreciated. Use a red window? For 6x12 count two 6x6 frame numbers. For 6x18 count two 6x9 numbers. Nick >>eyeball examination would give 48mm for the 645, 64mm for the 6x6, and >>93mm for the 6x9 (in metrics as are the framesizes). Are these correct? [quoted text clipped - 10 lines] > > Nick I most likely will stay clear of 6x12 and 6x17 in the beginning, so that leaves the problem sizes 6x7 and 6x8 for which there is no support in the medium itself. Unfortunately my camera can't handle those sizes, so I can't even measure their properties. I wonder how picky is the machine that processes the films. Jack > I most likely will stay clear of 6x12 and 6x17 in the beginning, so that > leaves the problem sizes 6x7 and 6x8 for which there is no support in > the medium itself. Unfortunately my camera can't handle those sizes, so > I can't even measure their properties. I wonder how picky is the machine > that processes the films. Do you mean develop the film? It doesn't care at all. A roll could have one long frame on it. It's only when it comes to printing that it's an issue. But with all the slight differences between the companies I can't see it being that big of an issue. I think somebody did a thread awhile back on frame size and various cameras. They all seemed slightly different. Nick > Do you mean develop the film? It doesn't care at all. A roll could have > one long frame on it. It's only when it comes to printing that it's an [quoted text clipped - 3 lines] > > Nick Some backs let you change the format on the fly without changing the film. I would guess printing those films would need a human to recognize the frames or some fairly advanced recognition software. Most likely the machine that does the printing will expect the frame to start within certain narrow parameters. Would like to know what those are so that I can make sure to stay within. Jack > I most likely will stay clear of 6x12 and 6x17 in the beginning, so that > leaves the problem sizes 6x7 and 6x8 for which there is no support in [quoted text clipped - 3 lines] > > Jack Why not build your own back but use the dividing mechanism from say a Mamiya Press back? > Why not build your own back but use the dividing mechanism from say a Mamiya > Press back? Excellent idea! Seems like I'm going to start a search for wrecks for parts to cannibalize. Had a look on that Sinar Zoom 2 Rollfilm Holder that Peter mentioned, to create something like that would be perfect. Jack >> Why not build your own back but use the dividing mechanism from say a Mamiya >> Press back? [quoted text clipped - 4 lines] > >Jack Another solution might be to use the Shen-Hao 6x12 back. Not a bad price and it is multi-format, and has different windows for 6x4.5, 6x6, 6x9 and 6x12. The native format is 6x12 and comes with a metal mask for 6x9. I guess you could order the other masks of have them made. - Mike Back to go to what kind of front? ;-) The simplest and cheapest would be to scavenge a folder, put in a mask (many were setup for using thin masks already), and use the existing film winding mechanics (and bellows etc.?). An example using "postcard" folders of the past for panoramic use could easily be re-masked with 120 film for any size format, see http://medfmt.8k.com/mf/postcard.html Some of the older folders also had a ground glass insert you could focus with too ;-) And the lens could usually be shifted up/down and tilted/swung in its mount, for much more flexibility than current consumer cameras ;-) instead of a back for a LF (or miniview MF) camera, you can simply use an existing film holder and scavenge a spare dark slide to cut as a mask for multiple shots (use a clear plastic overlay marked for the cutout position on the ground glass for focusing/composition). This is an old trick with panoramic shooters, use 6x12cm at top of frame, then flip the mask over and use it to expose the bottom half of the same 4x5" sheet. regards bobm  Signature*********************************************************************** * Robert Monaghan POB 752182 Southern Methodist Univ. Dallas Tx 75275 * ********************Standard Disclaimers Apply************************* >Back to go to what kind of front? ;-) The simplest and cheapest would be >to scavenge a folder, put in a mask (many were setup for using thin masks [quoted text clipped - 14 lines] > >regards bobm Bob, great idea and a blinding flash of the obvious. - Mike |
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