I wasn't certain this would work...

[Donald Qualls]

I've got an RB67 ProS. It came to me with a pair of Pro 120 films backs, one in 6x7, as expected, and the other in 6x4.5. Yes, this is a very heavy camera for 645, but the rotating back means at least I don't have to turn the whole thing on its side and figure out how to deal with the waist level finder in that position to shoot horizontal. For some reason, though, as far as I've been able to find, Mamiya never made a 6x6 back for the RB67.

Fortunately, Graflex did. Today I received a Graflex 22 roll film holder on 2x3 Graflok plate -- it's an older, knob-wind version, but it looks almost new. The framing system works correctly, as far as I can tell before actually running a roll of film; at least, it locks after progressively shorter knob twists as the counter works up from 1 to 12. There's some worn paint on the corners of the back and ends of the rib, where it contacts the camera back, and that's all the wear I can see. I wasn't certain until I got the holder in hand that it would fit the camera, but it does -- locks in solidly and when I take off the lens and fire the body I can see the 6x6 gate is perfectly centered in the 6x7 rear opening.

Of course, none of the interlocks work -- but with Pro backs on a ProS body, there are few enough of those that work anyway -- just the one that keeps me from firing the body with the dark slide in, which isn't actuated by the Graflex dark slide. I believe I can fabricate a pusher, equivalent to the ones on the RB67 dark slides, to actuate the interlock, which would also keep me from needing to use the overrides to release the lock slides to remove the 22. But until then, I have to actually pay attention to avoid exposing on the dark slide.

Given I also shoot 9x12 and 4x5, I can probably develop the necessary habit.

 

[shutterfinger]

Graphic 22 RFH were designed when film base was thicker and may have a .5mm to 1mm overlap especially with Fuji films whose film base is 3.5 mil thick, Kodak and Ilford are 4 to 4.5 mil thick.
A dirty gear train can cause overlapping/poor frame spacing. With a clean and lubed gear train that overlaps/has poor film spacing tape or bond .004 to .008 thick material to the transport roller on the take up side. An alternative is to add 1 to 2 layers of backing paper to the center core of the take up spool.

 

[Donald Qualls]

I don't think the transport roller is involved -- this one compensates even with no film loaded (hence transport roller not even moving). I just double checked it, and both rollers are perfectly freewheeling, independent of the gear train and counter. This counter frames like my Zeiss Ikon 532/16 (also designed when film base was thicker) does -- by "knowing" how far to turn. My 532/16 doesn't overlap, even when i start it an inch or so early to accommodate my mod for 12 frames.

I'll shoot a test roll, probably this long weekend, and see how the frames come out; if necessary, I can make up some inserts (to slip into the roll while loading) with a few inches of extra backing paper to pad out the spool diameter.

 

[shutterfinger]

READ https://www.graflex.org/helpboard/viewtopic.php?t=6391

 

[Donald Qualls]

READ https://www.graflex.org/helpboard/viewtopic.php?t=6391

I see Dan Fromm and 45PSS talking past each other, but nothing that convinces me there's any connection between the (freewheeling) feed rollers and the frame spacing. Changing the distance from one roller to the other won't change the amount of film pulled through by a given amount of spool rotation -- but changing the effective spool diameter will. This is simple geometry.

I've cleaned and modified a similar turns-counting advance in a Zeiss Ikon Super Ikonta B (532/16), and have similar mechanisms in multiple Minolta 16 and Kiev 30 and 303 cameras. I am familiar with the basics of turns-counting advance systems. I also have length-counting systems in my Kodak Reflex II and RB67 (the latter of which, in my 220 6x7 back, I've hacked slightly to make it work with film too narrow to actuate the original counter drive roller); I understand them, too (and they're mechanically simpler, with no cam or variable spaced stops needed to compensate diameter build-up on the spool).

The possible downside of padding the takeup with a paper insert (or otherwise increasing the spool diameter) is that this will make spacing wider at the start, but the thinner film will still make it narrower at the end (as the diameter starts off larger than design, but builds up slower than the cam is cut for). As 45PSS noted, the only real solution would be to replace the cam with one machined for modern film thickness, but if we can avoid overlaps and not run out of film length by padding the roll, it'll let us keep using these RFH without requiring a repair that's impractical and uneconomical.

 

[Donald Qualls]

Okay, I got out today in the Hanging Rock area and ran a roll of .EDU Ultra 400 through the Graflex 22. Operationally, everything seemed smooth. I also used a red filter for the first time ever -- we'll see if that did what I wanted to a somewhat tumbling sky behind the barn and tall tree.

I should be able to develop the film and have it drying before bed, but depending how long it takes to get my second enlarger with Chromega II head assembled, I may or may not have scans to show. I'll certainly at least be able to see if or how much the frames overlap.

 

[Donald Qualls]

Overlapping frames, not a problem. Spacing isn't perfectly even, but it's a 60-75 year old mechanical device. The only problem I have is that it started late -- there's excess blank film at the taped head of the roll, and frame 12 runs a couple centimeters off the end of the film. I wasn't terrifically careful setting the start mark when I loaded, but I also note that the counter wheel doesn't advance all the way to the S when I set it at the roll start; that seems likely to cause too much advance before reaching Frame 1. I may have to match up the instruction and pictures and open it up to see if there's something misaligned.

Of course, that extra 3-4 cm of leader might well have accounted for not overlapping frames. First thing I need to do is run another roll, load it with great precision and care, and see if that improves things enough to live with (oh, woe, I have to do more photography to test my equipment!). If I still get a late start, I'll have to work on it.

Meantime, when I have the 22 RFH mounted, my RB67 is now officially the Body Builder's Hasselblad. Conveniently, there's a very precise 6x6 frame already in the viewfinder, composed from the two set of frames for the rotating 6x7 back, but unlike a 'Blad, I can see a good bit of what's just outside the frame, all the way around. No surprises...

 

[shutterfinger]

Being you are processing your own film load the backing paper (wound to new orientation) aligning the start arrow with the start arrow (Graphic backs are picky, be within the arrow width of exact) and advance through marking each frame edge with a pencil onto the backing paper from frame 1 to the end. It won't be exact spacing as with film but will show the start point for frame 1 and any overlap. Using this test any overlap should be less than .5mm.

 

[Donald Qualls]

I just ran a roll of backing this way, and got overlaps by frame 8 and bad overlaps by 10, but 12 came up well short of the end of film hole in the Foma backing paper I used. But this isn't very indicative; without the film in the roll, we can be confident that what I saw was worse than real world by a lot more than real world is worse than original condition -- that is, no film is more loss of diameter increase than the change in thickness from 1950 to today.

What I can say with confidence, however, is that the first frame I marked is about half a frame closer to the film start tape than it was on the roll I just processed, which ought to be enough to get frame 12 fully on the film. That's only about half a turn less film and backing, so it'll be close on whether I get overlaps or not. I've got lots of backing paper on hand, though, so it's not difficult to make up strips a few inches long and keep a zipper bag of them in one of the pockets of my camera bag for use with this back. The RB67 is the only camera I have that this back fits, so I don't need to duplicate the package of backing strips, and they're reusable -- just pick them up off the darkroom floor after processing.

 

[shutterfinger]

Backing paper is .004 (4 mil) thick. Try a double layer from the film attach point.

 

[Donald Qualls]

Good thought. Heaven knows I've got some backing paper around...

 

[Donald Qualls]

Okay, I cut a roll of backing paper at the tear line on the tape, and at the crease where the film end was originally fed into the roll during confectioning. I then carefully rolled that strip into a full length backing, tail first, as if I were reloading a roll of 127 or 828 in original backing. When the "dummy film" ran out (right on the mark, within about 2mm of the original tape tear line) I taped it in place and finished rolling up. The resulting roll is at least close to the correct diameter -- I gauged by the grooves in the spool flanges where I'd trim for a 620 camera, which come out just about flush with the backing paper on a new roll.

I then loaded that dummy roll into my 22, set the start arrow as precisely as possible, closed it up and started the counter, then wound on and marked each frame with a pencil as it wound through.

I wound up with pretty consistent spacing (a millimeter or two of variation frame to frame, due to mechanical wear, most likely), no systematic change over the length of the roll, a good start position with 3-4 cm of unexposed "film" at the head, and a similar amount of unused length at the tail. This leads to the conclusion that I don't need to do anything to my 22 except load more carefully, so the arrows match up correctly.

I'm going to call this a win. I can now shoot 6x4.5, 6x6, and 6x7 in my RB67, as well as 35x70 (or 24x70 if I crop off the sprocket holes) on 35mm film. Electrical tape over the hinges has fixed the light leaks in the Mamiya film backs until I can get the foam replaced. Next thing I need to get for this camera is a 65mm lens (I currently have the 90mm and 250mm, plus a 2x teleconverter on which the jury is still out concerning optical quality). I bought red, orange, and yellow 77mm filters a few weeks ago. I need to get one more 77mm front cap, but those are easy to find and cheapish.

 

[ProfessorC1983]

I also recently purchased a well-used Graflex 22 for my 6x9 field camera with baby Graflok back. No major issues with film transport so far after a few rolls, however the thing does have a pretty bad light leak that's visible on the right-hand side of frames, so I assume it comes in from the latch side of the holder during the advance cycle.

Did you re-seal the used holder you bought, or do you have experience doing so? It's looking like it shouldn't be too difficult with a few pieces of peel-n-stick black velvet cut to size, but of course I'm wary of making anything worse.

 

[Donald Qualls]

I haven't resealed mine (yet). It appears to use geometric light traps in general. The light leaks in mine (bottom of frame, which is top on the camera, likely same as yours for cause) appear to come from pushing the back away from the Graflok surface due to interference with my finger (gets between the knob and the camera body) when I wind the film -- I solved it for the last couple frames of the roll by reinserting the dark slide before advancing.

My RB67 backs both leak at the shell hinge, which I've temporarily fixed with a strip of electrical tape over the hinge.

 

[shutterfinger]

The hinge and latch ends of the Graphic roll film holders have black yarn in the formed lip. It dries out, compresses, deterioates with age and leaks light. Yarn, felt, velvet can be used to replace the old light seal.

 

[Donald Qualls]

Thanks, @shutterfinger I've got a generic foam kit on hand, which I bought for my RB67 backs -- I'll have to take a look at the 22 as well. I like velvet better than foam for that, but unless it comes woven in strips (like ribbon) with a selvage edge, it's impossible to cut to size without producing unending traveling dust flecks -- and velvet ribbon seems to come only in wide sizes (to show off the velvet), not the narrow strips we'd find more useful.