One of the interesting things about 120 medium-format film is that there are a range of cameras which shoot varying size images with it. 35mm film cameras normally shoot a 24mm x 36mm frame size, but 120 can be 6cm x 4.5cm, 6cm x 6cm, 6cm x 9cm, or even 6cm x 12cm. Its a very versatile format. However, there's no reason you can't go even bigger than that! This Instructable shows you how to build a camera that uses a wide angle large-format lens to expose a 6cm x 17cm frame. That's an image with a nearly 3:1 image ratio, and a 100 degree view. At that size, it only gets four shots per roll!
This Instructable is to help you if you are interested in building our own 6x17 panoramic camera. The basis of this camera is pretty simple; a light-proof box that holds the lens the correct distance from the film, and a simple film transport system.
The lens I used is a Schneider Super-Angulon 90mm f8. This is a large format lens, which usually have an integrated shutter and aperture so this helps make the build process much simpler. Focal plane shutters are much more difficult to make large enough for a negative this size.
Head to the next step to see the design.
The design uses a lot of sheet metal and wood, as these were easy materials for me to work with (I no longer have milling machines and laser cutters at my disposal) and I had a bunch of material sitting around getting rusty. Luckily I had access to some sheet metal tools so it made it easy to work with the 18 gauge steel. You could achieve similar results with a band-saw and belt sander if you don't have access to a metal shear and brake.
My design uses a Schneider Super-Angulon 90mm F8 lens/shutter/aperture combo intended for 4x5 large-format cameras. This lens has a coverage of 216mm at the focal distance, so this will cover a 6x17 frame without issue. According to Schneider the flange focal distance of this lens is 98.8mm, this means that the lens must be held in parallel with the film and the distance from the surface of the film to the front face of the lens mount must be 98.8mm for optimal infinity focus. This number is a little bit flexible and I will admit that mine is not perfect. The image is slightly out of focus at f8, but the depth of field at f22 is high enough to make it a non-issue. My lens is probably pretty close to the hyperfocal distance of this lens, which is a good thing.
This camera opts for a simplified fixed-focus design, as I intend to use it for landscape and architecture photography only. At f22, the nearest object in focus will be about 10 feet away, which is perfectly fine for my purposes.
The film transport mechanism is just two knobs which turn a metal key that sticks into the top of a 120 film spool. The film is pulled from the supplying spool and rolled onto the receiving spool after each shot. Having two knobs makes it easier to roll because you can relieve the tension on the film by turning the supply spool and pull the film using the receiving spool. If you advance the film too far, you can always roll it backwards, too.
120 film uses a paper back which has numbers printed on it to tell the user what frame they are on. This camera uses the 6cm x 4.5cm markings but uses every fourth number only, starting with 2. Since the images are so wide the camera only gets 4 shots per roll, at markings 2, 6, 10, 14. I included extra windows to see the markings for 6cm x 6cm and 6cm x 9cm as well, in case I ever want to make a mask and use a smaller frame size in the camera. Many old 120 cameras had this feature built in.
Since the camera has a very wide angle view, I used a peephole from a door as a viewfinder. The finder is masked with some dark stickers to match the image frame.
If you have a lens already and want to make a camera that can use it, or you find the Schneider I used is too expensive or hard to find, that's no problem, but you're going to have to be prepared to do some design work.
Any lens can be used if you adjust the distance between the lens mount and the film plane to match the flange focal distance of the lens you have. The only crucial piece in designing a camera like this is that the film and lens are parallel to each other, and the correct distance apart. The rest can be done however works.
You don't have to make a camera from scratch, either. If you can find a suitable box you can use that to make it from.
If you have a lens and want to know more about it, the giant lens chart of modern lenses might help you out. Also take a look at the 6x17-specific lens chart. If you don't have a lens in mind, it might also help you select one to buy.
The majority of the camera is made from 18 gauge steel sheet. Aluminum can be a substitute if you're looking to save weight and make the work easier. Most of the pieces are flat and pretty simple. The film plane piece is the most difficult, it has some fairly complex bends and needs to be fairly precise, otherwise the film and lens won't be parallel. Many of the holes are countersunk to make the screw holes flush with the surface, which is crucial around the lens and the screws that go below the grips.
By printing the templates on the Design step, its pretty straightforward to layout and make these pieces.
I cut the bevels on the wood pieces using a table saw with the blade tilted 45 degrees. The holes in the edge are easily done by clamping the wood between the top and bottom plates, using them as a template. Some clearance was required for the rear element of the lens, this was done using a drum sander attachment for a drill press.
Once those holes are done the steel plates can be countersunk so the heads of the screws are flush with the surface.
Before doing any surface finishing, now would be a good time to test that the camera is going to work properly. Assemble the main body parts and attach the lens, then put some strips of scotch tape across the film plane. With the shutter and aperture open on a bright day you should be able to see an image projected onto the tape. This is just like the ground glass in a large-format camera.
The steel pieces are cleaned of rust and painted with flat black paint all over, and then a hammered finish black on the outside surfaces for durability and a nice appearance. The flat black will help minimize light reflections inside the camera which could cause anomalies in the image.
The wood was stained and sprayed with clear lacquer on the outside surfaces, and hand painted with flat black acrylic paint on the inside surfaces.
All of the edges need to be light-sealed as well as the internal separations that protect the film spools from exposure to light coming through the lens. I cut craft foam to size and sandwiched it between all the edges. I checked the light-tightness with a bright flashlight in a very dark room, looking for any light leaking through.
The inside of the back is lined with foam, and some extra foam is placed on the camera side as well. There is a thin piece of aluminum, painted black and glued to the back foam that serves as a pressure plate. It helps keep the film flat and in the right place during use. If the film isn't flat, the image can be distorted. The back also has some blue plastic over the film counter holes. Red is the ideal color but I didn't have a gel for that. Right now it serves better as a dust cover than a proper light filter. A big flat fridge magnet makes a great cover on the steel back.
I glued a 2-way spirit level to the top of the camera to help with getting the horizon level in landscape shots. A level with separate axes would be useful too.
The viewfinder attaches with guide pins and magnets to the steel top plate. The original one was fastened with screws and nuts, but I was having problems with it. The fixed viewfinder sticks up too far and the camera won't fit into any camera bags I have like that, so I made a removable one that uses the same mounting holes but uses magnets instead of screws to stay on. The guide pins that go into the holes make it return to the correct position repeatedly. The bracket itself is made of 1/8" thick, 1" wide aluminum bar, bent with a gentle 90 degree at the bottom. The magnets and guide pins are press fit into it.
This is the finished camera. I don't know what else to say about them so I'll let the pictures do the talking.
Using the camera is really easy. Just meter the scene, set the aperture and shutter speed on the lens and cock the shutter, look through the viewfinder and release the shutter with your thumb. On the Schneider lens the shutter release is perfectly placed to let you hold the camera from below with your right hand and press the shutter with your right thumb. The total weight is just over 1 kilogram.
I'd be more than happy to answer any questions (best I can) for anyone who is working to build their own camera.
The first roll I shot was pretty bad. There were a lot of light leaks and reflections inside the camera, so the negatives came out almost black. I was able to pull some images back in Photoshop but it was a struggle. After adding some more foam to the camera to properly seal it from external light as well as light getting into the film spool areas, the results were much better.