120 Film in 620 Film Cameras
The other day I posted an introduction to the Kodak Brownie Bull’s-Eye Medium Format film camera where I mentioned that the camera is designed to use the now defunct 620 roll film format. Fortunately, 120 roll film remains a popular and readily available format and is similar in just about every way to the 620 format. The difference is the diameter of the spool ends and the size of the spool holes that the film is wound around. As you can see in Figure 1 below, the 620 spools are smaller in both respects.
Now, at least in the model of Bull’s-Eye that I have, a 620 spool is needed as the take-up spool. This is because the winding knob (film advance) nub inside the camera requires a smaller (620-type) spool hole to actually turn the spool (to advance the film as each picture is taken). The other spool, in the loading chamber, only needs to be secured enough to stay in place as the film advances. Of course, the film still needs to fit in the chamber in the first place, requiring that it be previously re-spooled onto a 620 spool, or trimmed down. Trimming the 120 spool is easy as it’s made of plastic.
Frame Number Magic
The Bull’s-Eye and other cameras that deliver 2 ¼ x 3 ¼ in. images off a 120 roll, will only produce up to 8 images. You’ll see the frame numbers on the back of the film protective paper through the red window on the back of the camera. When you get to number “8” you’re done. However, on other cameras, like the Holga 120N for instance, you’ll see more frame numbers as you advance the camera. Reach number “12” or “16” and you’re done. How is that possible?
Numbers are printed on the paper backing of the roll of film in three different areas and distances from each other. Frame number windows on cameras are positioned to coincide with the corresponding row of numbers, to match the number of frames the camera can expose based on the size of negative image it produces. The Bull’s-Eye frame number window is located so that it displays the row of numbers that count up to 8, spaced so that you don’t reach the next number until you’ve advanced the film far enough to clear the previous exposed area. The Holga has a selectable window so you can see the correct frame numbers based on the format you’re shooting (that camera allows you to shoot 6×4.5 or 6×6 format, 12 or 16 frames respectively).
Test Roll Reminds Me It’s 1/50 Sec or So
On the first roll I shot, I noticed that my images were just a little on the blurry side due mostly to camera shake. However, results were generally impressive with the Tri-X 400 film. The camera has its shutter speed set at 1/50 sec. or so and an aperture of approx. f/11. These settings can’t be changed. My handheld light meter gave me readings from f/32 to f/8 and exposures were good all around because film is pretty forgiving when it comes to exposure. I’m loading up with more film tomorrow–this time color film–and I’ll post the results soon, with less blur hopefully.