SLIDE DUPLICATING
By Mike Ballentyne (Area 20).
For several years I experimented with various duplicating techniques including down-rating the film speed with pull processing and pre-flashing. Eventually I was able to make fairly good copies, but the contrast was never quite right, though better than many commercially made copies. They were still not good enough to send to publishers.
Then I saw the duplicates made by two friends, in each case almost indistinguishable from the originals. They both generously told me how to do the same. The difference is the film stock and equipment, and meticulous techniques. One uses Ektachrome S0366 which is balanced for daylight or flash, the other uses Fuji CDU balanced for tungsten light. Both films are E6 process, and can be bought from Jessop, the S0366 in 36 exposure cassettes and the CDU in 30m length. The CDU is much cheaper if you need that many dupes. These films are slow, high resolution and low contrast, with good exposure latitude and are designed for duplicating.
I use a Bowens Illumitran with Contrast Control Unit, which is quick and easy to use. It operates on the method of fogging described on page 7 of CRCN 65. The Illumitran allows the required exposure to be given, the magnification to be varied and the amount of fogging and hence contrast, to be controlled.
After the initial test film to set up for the type of copy film, type of original etc. copies can be made quickly, with colour and contrast adjusted as required. A second copy may need to be made if precise colours are wanted, though I find that unless the copy and original are viewed side by side, small variations are not apparent. Remember the colour of the natural light in most shots varies greatly, resulting in similar variations in the original slide.
I use Fuji CDU film with orange filter from Jessop`s "Powerflash Colour Correction Filter Set", very cheap, over both flashes. It is useful to have full sets of yellow, magenta, and cyan filters, in grades 5, 10, 20, 30, 40 and 50. Optical quality Kodak filters are very expensive and unnecessary. A set of Cibachrome filters at a fraction of the price will do the job, placed over the main and fogging flash.
I process the CDU in Photocolour Chrome 6, using a Jobo CPE2 processor. I always use a one minute wet preheat and have not experienced the overdevelopment mentioned on page 5 of CRCN 65. The first CDU film I processed had blacks that were very deep red, while the Fuji 50 in the same tank was normal. Fuji said that probably the three bath process is not suitable for CDU. Photocolour said it sounded like insufficient development, despite six minutes in the Jobo rather than the recommended four. I increased the time to seven and a half minutes @ 38C which cured the problem. This much extended time does not seem to adversely affect Fuji 50 & 100 or Ilfochrome 50 processed at the same time.
My first shot on each roll is a test slide, with black, white, grey`s and colours, so I can check filtration, contrast control and processing. I make notes of each exposure, which sounds elaborate but enables me to quickly discover errors and to make appropriate adjustments with some certainty. I do this on a record sheet and find the short time taken to be well worthwhile.
Thus I can go back to any dupe I have made and repeat it identical or adjusted.
I find that part used Chrome 6 solutions, in completely full plastic bottles, keep many weeks at about 15C. I have not found any deterioration after three weeks at 25-35C on a yacht in the tropics.---------------------------------------------------------------------
ANOTHER RED SHADOW
By Mike Ballentyne (Area 20).
The account on page 11 of CRCN 65 reminded me of a problem a few years ago. I made a paper safe for storing B&W paper. I used 3mm plywood, painted each side with black emulsion. I tested for light tightness in the usual way with a test strip inside for several minutes, partly covered by a coin. Results - no fogging. Then I used this safe for Cibachrome paper and suffered red fogging. A test strip gave a beautiful medium red with black coin shadow. The light from a 6w bulb about two meters away was fogging the Cibachrome through the black painted plywood. Lesson - you cannot be too careful.
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