Images, from 8 mm to HDTV
By Walter S. Ciciora,
Ph.D., Recognized Industry Expert on
Cable and Consumer Electronics Issues
Photography, movies and television have a closer relationship than many appreciate. There's even a society dedicated to this relationship–The Society of Motion Picture and Television Engineers (SMPTE). (See www.smpte.org/.)
The digital compression of still pictures came before the digital compression of moving pictures. The Joint Photographic Experts Group (JPEG) applied the mathematics of the Fourier transform in an efficient manner for still pictures. JPEG was also applied to motion pictures by compressing each frame individually, without removing the frame-to-frame redundancy. If you have a digital camcorder, you are using a form of motion JPEG. The DV format is available in 25 Mbps, 50 Mbps and 100 Mbps versions. The Sony Digital-8 format is electrically compatible with the DV format, but uses a premium version of the same 8 mm tape cartridges as the analog 8 mm and Hi-8 systems. Starting with this firm foundation, the Moving Picture (not Motion Picture, a common mistake) Experts Group (MPEG) found ways of reducing the redundancy in the temporal direction. MPEG-1 first attacked progressive scan moving pictures for computer applications. The more challenging case of interlaced video came later as MPEG-2.
A recent personal project involves the conversion of old family 8 mm and Super 8 movies to VHS tapes and DVDs. This combines many of the elements discussed above. My family, my parents' family, and my wife's parents' family accumulated around a dozen hours of 8 mm and Super 8 home movies, along with a little over an hour's worth of purchased cartoons. This totals about 12,000 feet of film. Each individual film is 50 feet long and runs for about three minutes. That comes to about 1,000 feet of film per hour.
The oldest film is from the 1940s and is in black-and-white. Men in military uniforms are common in those films. As image quality goes, this is not HDTV! But for emotional impact and heart-warming effect, it can't be beat. "Content is king!" Showing these to older relatives brings back memories, long stories and some tears. It's a good idea to have an audio tape recorder (or the camcorder) at hand to capture their precious comments.
It is not possible to fully appreciate the wonders of digital video and HDTV unless you've experienced 8 mm film. It seems hard to believe, but the early 8 mm cameras had nothing electrical in them. They were actually driven by a wind-up spring. Exposure and focus were manually set. The film spool was manually threaded through the film gate to the take up spool and ran for a minute-and-a-half. Then, the camera had to be opened and the film spool turned over and put back onto the feeding spindle for another minute-and-a-half. Film sensitivity was measured with a logarithmic ASA scale. Current 35 mm color film has a typical ASA rating of 200. "High-speed" black-and-white film has a speed of ASA 400. The earliest 8 mm movie film had an ASA of 10, followed by 25, and then a "fast" ASA 40. My recollection is that film plus processing for those three minutes cost around $8.00 (not adjusted for inflation).
These aspects help explain the poor quality of these images. Short filming time and relatively high expense motivated dizzyingly fast pans. The low film sensitivity meant bright lights. My uncle had a light bar with four flood lamps. Later, halogen lamps provided an answer to the weight of the light bar, but in all cases, the bright lights forced subjects to squint or turn away. Many people hated the lights. The lack of automatic exposure resulted in a lot of bad exposures–manual focus was problematic. This was exacerbated with "zoom" lenses. Invariably, the focus was set at normal or wide angle and was lost during a zoom to telephoto. The camera operator had no accurate indication of what was being filmed. Consequently, close-ups tend to have only parts of faces or less than was intended. If the film was loaded in bright light, some of it could leak into the edges of the film, giving it orange borders. It was also possible to reload the same film and get a double exposure.
Those were challenging economic times. Sometimes, to save money, we'd use off-brand movie film and "drugstore" processing, yielding off color and over or under developing. The waiting time between submission of the film and its return was an excruciating week, a rather long feedback loop! The degree of fading of the colors over the years is another uncertainty.
A major advance came with Super 8 film. 8 mm film starts out as 16 mm film with sprockets on both sides; it is slit down the middle to double the length and ends up with sprockets on just one side. Super 8 film reduced the size of the sprocket holes and increased the film area by 50 percent. The Super 8 film came in a cartridge so that it did not have to be threaded through the film gate in the camera. I can't remember if the cartridge had to be turned over halfway through–I think it did. My Super 8 camera was battery-driven and had electrical exposure control, but not auto focus. The technology of auto focus is more challenging than simple exposure control. Of course, exposure control has become more sophisticated over the years, too.
We have come a long way from these early images to the present technology of digital TV and HDTV.
Have a comment? Contact Walt by e-mail at: Walt@Ciciora.com