It’s been a little while since I posted anything on the DIY Large Format Project! Last time, I showed how to make your own 8×10 film holder. So this time, I’ll take the next logical step and show how to make your own 8×10 camera back for your film holder.

The purpose of a camera back is to provide a home for the film holder on the camera. It should be a fairly snug fit with the film holder, and it needs to form light-tight seals with the camera body and film holder when in use. There are a few main designs for camera backs, but I chose to go with a side-slider type. In this camera back, the film holder slides into the camera back from one open end.

Materials

As always, we’re using really basic stuff here. You should be able to purchase all of it at a local office supply store.

• Foam core: black if possible, and a 20×30″ slab should give you plenty to work with.
• Ruler: metal and over 12″ will make life easier.
• Hobby knife: and make sure you have extra blades, they wear down.
• Glue: white school glue is fine if you don’t mind waiting for it to dry.

Build Instructions

I have to admit right up front that the camera back shown in these photos is basically garbage… I need to remake it. But my instructions will tell you how I would do it the 2nd time around (and I’ll point out the spots where I messed up).

STEP 1: Cut the front and back faces

Lay down your film holder at the corner of the foam core and trace it to make an outline (add and extra 1 or 2 millimeters to give yourself some cushion). Cut out that piece and make a 2nd. These are the front and back pieces and they should be very close in size to each other and to the film holder.

Mark and cut a hole in one of the pieces that matches your film holder. Again, give yourself 1 or 2 mm extra room so you don’t block the film with it. After cutting the hole, check it against both sides of your film holder to make sure it will work.

STEP 2: Cut the side and bottom faces

Now stack your back piece, film holder, and front piece on top of each other and measure the thickness. You might want to add a light book to the top of the stack so the foam core lays flat. Once you have that measurement, mark out some strips of foam core that are as long (or longer) than the long edge of the front and back pieces, and as wide as your measurement. You need two of these to use as the sides. Do the same with the remaining short edge to create the bottom piece.

This is where I really messed up, so pay attention. My film holder is somewhat flexible due to the construction materials… so it gets a little thicker when the dark slides are in place. I measured the thickness without the dark slides and I ended up making a camera back that was way too small for my film holder (unless I plan on using it without dark slides). So I’ll have to remake it a little bigger this time. With the design of this camera back, you also don’t want it to be too sloppy because it will leak light — so it’s a fine balance between too small and too big when cutting out these side and bottom pieces.

STEP 3: Glue the bottom and sides to the back

Now that you have all the main pieces cut out, you can start to glue things in place. I started with the bottom piece (on the short edge of the camera back). Apply glue to one short edge of the back piece, lay it down on some newspaper or wax paper, and place the bottom piece down against it as shown in the photo above. Use a few books to hold things in place while the glue dries.

Once the back dried, I glued the two sides in place with a similar method of gluing and book stacking. Now for the important part…

STEP 4: Glue the top in place

Place your film holder down (with dark slides in place!) against the back piece and push it all the way into the camera back. You should have extra side and bottom material sticking up above the film holder — about the thickness of the foam core you’re using. Now apply glue to 3 edges of the front piece (the one with the cut window) and place it into the assembly thus far.

the film holder might want to push it up a little, so we’ll use a light book to keep it down. Before placing a book on top, you might want to apply a little extra glue around the edges (but not too much because you don’t want it dripping down and gluing the film holder in place). At this point, I laid wax paper over the top and gently placed a book over it to hold things down.

After drying, the film holder should slide out with a little bit of resistance. Slide it back in and make sure everything fits into place.

STEP 5: Add light seals

After you verify everything is sized correctly, you can add some extra light seals to fend off the leaks. I haven’t done this part yet because I need to remake mine, but I’m planning on doing a couple of things. First, I’ll put a layer of tape around the three glued edges just in case there are any holes. Then I’m thinking of putting a thin layer of felt on the surface that seals against the open end of the film holder — this is the main location where light can sneak in. I might also add some extra foam core near that open edge to create a more robust light trap, but I’ll wait until I mount it up to the camera body.

STEP 6: Mount to the camera

This will be the next topic I show/discuss in this project. After I remake or repair my camera back, I’ll show you how I mount it up to the camera body (cardboard box). At that point, I should have a usable camera back and film holder so I can get out and take multiple shots in a single session… I might even make another one or two film holders if I find the time.

Is anybody else out there still building their DIY-LF cameras? Have you guys made any improvements yet? What are your next steps?