PHOTOpro magazine has frequently explained the benefits of duping up your 35mm transparency work to 6 x 9cm on 70mm film to increase your sales. Side by side on the lightbox, the large format transparency will outsell any 35mm.
Diffused illumination used in most duping systems has the effect of softening the saturation of colour and sharpness of the image. The ACT Liquid-Gate Point Source Duplicator, which solves this problem, has been installed by a few labs with the technical know-how to understand its benefits, and the financial clout to buy the kit. When, however, did you last see this service promoted to you as a potential user by a colour lab?
Admitting some frustration at how little-known their superior duping system remains amongst photographers, manufacturers Advanced Colour Techniques of Rhayader, Powys, Wales have decided to sell direct. Before now they restricted their own service to libraries or clients with thousands of images to be copied at a time.
Apart from the quality of the dupes, which is far superior to anything else I have seen, ACT can conceal scratches on the film base that would otherwise mar the dupe making it virtually unsaleable. This is achieved by suspending the cleaned original in a special oil in the equipment's liquid gate. The oil is identical in refractive index to the film-base, and fills in blemishes and scratches.
The saturation and sharpness of the dupe are enhanced by making three exposures through narrow-cut RGB filters with a point-source xenon arc strobe as illumination. Chromatic aberration is effectively eliminated and colour correction is easily controlled. The original transparency is imaged by a high-quality lens to a film back handling sizes from 35mm to 10 x 8". - Steve Newman