There is abundant information about film manufacturing markings. Another marking sometimes unknown or overlooked, are the processing markings. Kodak, at processing time of Kodachrome film, stamped 8mm film with the year and month of processing. The markings vary in visibility, some are quite small and easily missed, others (like the one below) are easy to spot. As part of capturing all the relevant information about 8mm film, this is a very useful time reference which should not be overlooked.
One of the design aspirations of this project is be the ability to handle Develocorder films, and it is appropriate to elaborate on the particulars of it.
The DEVELOCORDER trademark was first assigned, in 1961, to GEOTECHNICAL CORPORATION. The Develocorder was a recording device used by the network seismology from the 1960s into the 1980s. The USGS, among others, has tens of thousands of films reels (maybe even more), for records of that period, most of which remain in good condition. The recording media was 16mm wide sprocketless black&white film. Typically each reel is 100 feet, and it stored up to 20 seismic stations and time codes in strip chart mode, for 1 day of continuous data.
"One of the key pieces in the early Menlo Park micro-earthquake monitoring program was the Develocorder, a 20-channel photographic recorder that continuously captured seismic-trace inputs onto 16-mm reels of microfilm. The Develocorder automatically fixed and stored the microfilm so that a record showing the 20 channels of data was available for viewing within 11 minutes of receiving the data inputs. In 1967, a Develocorder was delivered to HVO (fig. 5). By the end of the year, it was in operation and became a mainstay of HVO’s seismic monitoring effort until 1997."
According to another paper "DigitSeis: software to extract time series from analogue seismograms", M. Ishii and H. Ishii, it is defined as follows:
"The “Develocorder-style” seismograms are defined as synchronized seismograms from multiple components or stations recorded on a single medium (Fig. 8). Another feature of these seismograms is that one or more of the traces are dedicated to timing, i.e., they do not record ground motion, but provide time information. Develocorder-type recordings became popular in the 1960s with development of the ability to accurately telemeter data from distributed stations back to a central location."
These records have been the subject of renewed interest, and rediscovery, thanks to the use of deep learning techniques to process and detect new seismic events. For more information see: "Seismology with Dark Data: Image-Based Processing of Analog Records Using Machine Learning for the Rangely Earthquake Control Experiment" K.Wang, et. al.
This renewed interest, creates the necessity to have digital access, which requires digital preservation of these old records.Needless to say, the US is likely not the only place with DEVELOCORDER film records.
I hope that providing a cost-effective, and technically capable blue-print to build a simple scanner compatible with this old film format provides a benefit to the USGS, and other world-wide alike institutions holding and preserving film seismological records.
Hopefully, it would also open technical collaboration with other institutions (in addition to the DIY 8mm/16mm film community). Future improvements and enhancements of preservation efforts can then be for the benefit of both communities, seismic and moving image film records.
Needless to emphasize... it is all film, time will not discriminate on taking its toll.