Charles 46277 Loc: Fulton County, KY

Long ago I bought a 6x12 Chinese roll film back for Graflok 4x5 camera back, but never figured out how to use it. The numbers never came up in the red window when I rolled film--I think now I must have had it going the wrong way. But I don't know what numbers to go by--the film manufacturers did not make the 120 film with numbers for 6x12, so you have to know what numbers to stop on. Anybody have knowledge about these? The brand is Guohua, GH6x12, but that name is no longer on ebay or even in Google. However, any 6x12 back with the red window ought to be the same in this respect. It is plastic, but looks like it would work.

Kuzano

Three rows of numbers on the back of the film. One row is every number makes a 6X6. So finding which row that is, then every second number to come up in the hole proper row holes would give you 6X12. That would be if your back is multi format and shoots 6X6, 6X7 and 6X9. then the doubling on the right set of ruby windows would give you 6X12. If the back is single format with only one number window, then you would have to catch every second instance of the number in the window. Kind of like you were doing a multiple exposure. Since 120 roll film was never marked for 12CM, that's sort of what you are doing. Pulling two 6X6 frames into the frame in the film back. 6X6 normally gives 12 frames (square) on a roll film camera like a hasselblad. Therefore, you will get a total of 6 frames at 6X12 on a roll. Two squares for each advance of the film. Advance two frames to fill the 6X12 window when you pull the dark slide.

Ima cheap bastid... I just cut down one dark film slide. Use4X5 DDS, pull the dark slide and slide in the shooting template. Little more management. I used to do the same with a 5X7 large format camera to get 4 nearly 6X14 images per loaded DDS film holder.

Charles 46277 Loc: Fulton County, KY

So 2 6x6 frames are used for each shot, and this one (6x12 only) should line up the first picture when 1 appears in the window--the window is over the second half of the 6x12 frame, so 2 would already be on the frame also. Then I advance to 4 (skipping 2 and 3), which also puts 3 in the frame, and so forth--that gives 6 takes on the roll.

We are assuming the red window exposes the 6x6 line of numbers... It should, as the gadget only does 6x12, and no other row makes sense.

I have heard of your method of shooting two on one film. In fact, I have a Graflok split back that gives two 2x3's on one film. The advantage to the 6x12 is that I also have a 6x7 back, so I can keep one roll for each format, regardless of the shooting that comes up--plus the 4x5. I also have an adapter for Canon digital on the 4x5.

Charles 46277 Loc: Fulton County, KY

Sorry--the split back makes two images 2 x 2.5, not 2x3.

User ID

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If the red window is over the far side
of the 6x12 frame, then you just keep
centering the even numbers.

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Pablo8 Loc: Nottingham UK.

I have 6x9 and 6x7 backs for my 5x4 cameras, so do not have your problem with 6x12 back. Would have thought that to use the 6x6 numbers, but only the even numbers to show in the window...2;4;6;8;10;12. You could of course, load the backing paper roll from a used film, and in daylight mark where the frames 6x12 occur, starting at the first full 6x12 frame and what numbers are at the red window. I assume you do your own processing and will have used backing paper rolls, But even worth using an unused film, to get the spaces correct between the 6x12 frames.

Kuzano

You can test either theory by using an exposed roll of film or an outdated roll. Simply pull the dark slide and run the back through it's paces. At each spacing of the test roll, use a sharpie and mark the ends of the frame. You should then have the idea of correct spacing including space between frames. This is, of course, done off camera.

Note: Again a 5X7 camera allows you to cut one dark slide for a 6X14 on each side. Then you can get on one DDS side 2 frames of 6X14, flip and 2 more on the other side for a total of 4, same as a roll of 120 on your chinese back. However, since you are using halves outside the center line you must manage perspective control OR rise and fall to get it right.

No matter how you tackle it, using your Chinese back or going for multiples on a cut out dark slide, it's a spacing management issue.

Good luck

Lars