Graflex 4x5 bag mag info

[walter23]

Anybody know what the so-called T-distance is for the graflex 12-shot 4x5 bag magazine? (ie, the distance from the outside edge of the holder (film side) to the actual film plane)? I can measure, but I was hoping for an official specification.

Also: any suggestions re: the red window? Is it safe to use this to count exposures, or was this built with orthochromatic film in mind? I do the red window trick with one of my 120 film cameras, but I'm not sure how light-proof the back of these bagmags are.

Finally: what's the proper method to open the back to get to the film septa? It snaps open if I pull hard enough but I'm afraid I'm doing it wrong - maybe I should slide it one way or the other before I pull, or maybe there's a release latch I overlooked?

[David A. Goldfarb]

The T-distance should be the same as for a regular filmholder.

I use the red window on my bag mags with no problem, and I keep the shutter closed when I don't need to count.

Opening the back depends on the design. I have 5x7's in two designs, and the 4x5's I've seen look the same. An older one has two latches on the sides that open in an obvious way. The newer one has a button under the leather covering on the side opposite the bag. Press the button to release the latch that holds the back on. One attraction of bag mags over Grafmatics is that the exposed sheets are at the top of the stack when you open the back, so if you don't shoot all 12, you can just remove the exposed sheets without disturbing the unexposed sheets.

[Glenn Thoreson]

The button is front and center, as Dave said. Be very careful with the septums. They're easily bent, which renders them useless. Be sure they are inserted with the proper end facing forward. I'd have to look at one of mine, but memory says open end forward. If the numbers are backward, it's wrong, anyway. Be sure to very carefully and thoroughly check the bag for light leaks. Remove the cover and septums and use a bright light source to shine into the bag from inside the chamber. If you manipulate the bag in a dark room, you should be able to see any leaks. I use a mini mag flashlight for this check. Bags are seldom in good condition, due to old age. Be sure the rod that pulls the septums back into the bag is straight and operating smoothly. The red window is pretty safe, as the septums lie on top of one another, making it more difficult for light to get to the film. Care for the bag by giving it a good coat of paste wax shoe polish now and then. Enjoy!

[walter23]

Great, thanks. I picked this up on ebay on sort of a whim. It was part of a "pinhole box camera" which was well built except for the fact that someone mangled it and filled it with sawdust by drilling presumably for a tripod socket. I'm going to outfit it with a simple pinhole zoom mechanism (two nested boxes) and maybe at some point a cheap and small wide angle lens with a helical focus. The world's most portable 12-shot LF setup :)

[Captain_joe6]

From what I've heard. the T-distance for Graflex-type holders (the bag mag, the slotted two-sided holders, etc) is actually about 1mm more than compared to Graphic and Graf-lok type (regular film holders, roll backs, anything else in recent production, etc.)

Just eyeballing my modern fidelity holders against one of my bag mags, there is a noticable difference between the two. Not much, but its there, at least to my eyes.

As for the red window, I've never had a problem with it in any of my seven 4x5 magazines. I replaced a few of the bags with new ones made of black leather-textured vinyl for the outers and a black nylon blend for the inners. Very nice to work with, especially with a little bit of extra room that I designed in to them. Only problem is that the vinyl gets stiff when I'm out in cold weather, but not so much that I'd worry about it. It's noticable, though. Best part is, after the second or third replacement, I could replace a bag, from stripping the old one, cutting the new one from my pattern, sewing it all together, and replacing everything, in about 20 minutes.

What I would watch out for are the light traps. I've had troubles with a couple of mine, but I think its only been when there's light shining directly on the trap while I'm removing or inserting the slide.

As mentioned before, you need to make sure that the septums are as flat as possible. I spent a good deal of time making sure mine were all as flat as I could get them, but be VERY VERY gentle in any adjustments you have to make. And if you get another magazine or two, probably not a good idea to mix septums between the holders. I've got all mine adjusted to work just right with the magazine they came in, and thats the way I'm going to keep it.

Once you open them up and see just exactly how everything works, they're incredibly simple little devices, but incredibly fun to use!

-Patrick

Once you open them up and see how it all works,

[walter23]

Still working on this project - I have most of the wood cut and the design pretty much worked out. It'll extend from 35mm pinhole ultrawide, up to 170mm to let me use my 150mm lens, and compact down to a cigar-box size. Weighs less than my rodenstock 90mm lens (lenses & bagmag not included).

I've measured 1/4" (without the use of a micrometer, alas) for the film-flange distance on the graflex holder. This is convenient because I can use 1/4" wood to build a frame for my ground glass and it should register pretty close. I realize it won't be exact but I'll try to get it as close as possible and do some testing before using it. But I want to build a regular 4x5 film holder adapter for it; I may, at times, want to bring a few extra holders along (e.g. with a different type of film than my graflex bag mag is carrying, or for longer trips, etc).

The T-distance for a 4x5 film holder is 0.197" (from searching the archives). So I'll need a shim to push it back an extra 0.053" from the mount to get it into the bagmag plane (0.250" bagmag - 0.197" filmholder = 0.053"). Anyone ever done this? Any suggestions for material? Have I got the numbers right? My best guess so far would be to sand down some 1/16th birch plywood and use that, though such thin wood will be really weak. Is it possible to order sheet metal in precise thicknesses like this? Any other ideas?

Because this camera is supposed to be extra portable, I don't want to build a different back for regular film-holders. I'd rather just have a simple shim and adapter so I can use them as-is in a pinch, with my ground glass set for the bagmag.

The camera is mostly for bag-mag use anyway so if I can't find an easy way to do this I'll stick with the bag mag and forget about regular holders.