Setting Up a Video Analyser.
The effectiveness of an analyser largely depends on the stability of the image. The grader uses a test negative, usually an LAD negative, but in the past the laboratories sometimes made there own by exposing film to a stage set with a grey scale and a local girl’s flesh tone. The Society of Motion Picture and Television Engineers in the USA, Kodak and the British Kinematograph Sound and Television Society produced standard negatives that were often used for this purpose. They often had curious names that reflected their models or their origins, or the significance is simply lost - China Girl, Julie, Katrina and so on. Some had their origins in standard negatives produced by film manufacturers for still processes or graphic arts processes like Kodak’s Dye Transfer Process.
The modern standard negative is Kodak’s LAD negative - the Laboratory Aim Density negative, used for analyser set up and for duplication set up. Photo The negative is placed in the analyser gate and the calibration adjustments made to produce a good image, with the printing conditions set on the analyser at 25, 25, 25 [R G B}. The negative is then printed to produce a visual match with this image - an extremely difficult judgement to make, - and the printer trims (more details in section on printing) adjusted to achieve this result at pre-set values of the printer lights, also at 25, 25, 25 [R G B] [often called 25 across].
This simple explanation covers a morass of problems that has beset the laboratory industry for years, and which any client whether archive or not, and including internal archive laboratories, needs to understand
- The picture displays on all analysers never look like the film image when printed; they normally look like a video picture. The result is that however the grader makes mental adjustments he or she can never see the print, as it will actually appear, so that errors are inevitable. The correction is rarely precise. A well set-up digital telecine with various secondary corrections and masking facilities can generate a film-like image but this has happened only recently and at a price well outside that of a film laboratory. A film scanner display on, for example, a Cineon display, can also generate such a picture but at 10 seconds per frame, the operation would take too long as well as being even more costly.
- The fixed gain/contrast characteristics of analysers rarely fit the products of the day and even reversal-reversal displays are rarely as accurate as pre-grading with hand held colour filters!
- The Hazeltine in particular has a very poor quality image.
- Some analysers use non-standard components, so that they are awkward and often costly to maintain.
- Only the Hazeltine and the Filmlab analyser can be fitted with 16mm A & B gates [and no analysers has 35 mm A & B gates].
- Ideally an analyser should
a] have a motion drive facility, like a telecine or editor to show the moving image
b] should have frame store to allow the retention of frames from elsewhere in a production. Few have these facilities. - The image must be absolutely stable and not drift - few are as stable as is needed.
More on LAD
Using LAD to control
print quality