Ewesly / 70 mm Film Transport
The film holder for these exposures is a magazine that was designed to fit on the back of a Long Roll Camera. A typical Long Roll Camera's job would be when photographers would come into a school and take pictures of everyone.
This back was made by Beattie-Coleman. I purchased it from Helix Camera around 1984. My friend Tom Kovarik, electronics technician at FermiLab, built a control box for it which powers up the unit with 120 VAC by way of an on-off toggle switch and equipped with a momentary push-button switch to advance the film for me. I later added a solid-state switch to the control box when I automated the advance trigger.
The lovely crackled black finish got removed at the same time that some rust was removed! What a shame!
An AC motor drives the take up spool on the left to shuttle the film from the supply spool on the right. One complete revolution of the roller on the left moves the film one full frame by a cam pushing a micro-switch under the base plate. A pressure plate pushes the film forward into the open aperture. It is surprising that the film is stable enough during exposures as it is held only by the edges!
The back's dark slide is in position, so that the transport loaded with film can be positioned with the room lights on. A piece of cardboard with centering marks helps to position the transport in the proper place, or to align the beams to the back.
There is a counter on the side of the transport to check how many were shot or how much is left on the roll. It is the dark rectangle on the lower front of the unit, unfortunately this photo does not show the numbers. There are about 300 frames on a 100 foot roll of film.
Here is a view of the various control devices on their cart. At the top left is the el-don (nee Jodon, that's a sticker THE Don Gillespie put on the box when refurbishing it) driver for the Scanning Fabry-Perot Spectrum Analyzer; under it is the Uniblitz Shutter Controller Driver; the old school closed circuit black and white monitor shows what its attached camera is pointed at, in this case the alignment card in the 70mm back. The remote controls for the HVAC and tunes are watching the TV. The storage oscilloscope on the right monitors exposure time, and under it is the controller to power up and advance the film back.
When in run mode, the Uniblitz shutter driver makes the exposure, then when the exposure is terminated, the shutter driver sends a signal to the controller made on a Radio Shack Electronics Lab breadboard (that I had bought for my sons many Xmasses ago) which then holds in the solid state relay in the back's control box to get the transport started moving the film, which will stop on its own after one frame is advanced.
The breadboard controller waits for the appropriate settling time, then sends a signal to the Uniblitz controller which makes an exposure, and starts the series over again. With a 50 second settling time and a fraction of a second exposure time, that translates to approximately 5 hours to run through the whole 100 foot roll.
If anyone in the group is interested in making a run of holograms in this format, please contact me.