Re: Densitometer Value/Tricolor Processes


Richard Lahrson (tripspud@hooked.net)
Tue, 23 Feb 1999 09:37:15 -0800


Sandy King wrote:
 Because
> the readings are analgog on the 877 it is somewhat difficult to read the
> higher densities since they are closely spaced on the dial. However, there
> is no doubt but that one could do very precise work with this old
> instrument.
>
> BTW, my unit came with a nice plexiglass cover that sits nicely over the
> top of the densitometer. Does anyone know if these tops came original with
> the unit?
>
> Sandy King

Greetings Sandy!

     A quote from the Weston Analyzer Model 877 manual:

                "If it is desired to measure densities greater than 2.4
                the range of the Densitometer may be extended by placing
                a negative having a density of 0.4 or 0.5 over the aperture
                'E' and adusting the rheostat 'C' until the meter indicates
                zero density. Remove the negative and use the densitometer
                in the normal manner but add the value of the density used
                when working the above adjustment. For example if the density
                used was 0.4 and the meter readomg obtained on the negative
                being measured is 2.3 then the correct density is
                2.3 + 0.4 = 2.7."

     So higher densities can be read more accurately with the above solution.

     There's no mention of the plexiglass cover in the manual. However, it
lists the following:

                       1. Multiplier disc for contact printer measurements.

                2. Negative step wedge (small) for enlarger.

                3. Negative step wedge (large) for contact work.

                4. Positve step wedge (grey scale) for color work.

                5. Paper data sheet.

                6. Plotting paper for time-gamma curves.

                7. Exposure Guide.

     The Multiplier is 10 times. The Exposure Guide is a dial calculator.
If anyone has a dial calculator, could they contact me off list? I'd like
more information to, possibly, contruct a similar device "home-made."

     The manual is of some further interest to the alt community in that
it includes sections on making tricolor separation negatives for
Dye Transfer and Carbro Prints. Are there any workers on this list that
still attempt these archival color processes? Or any workers using ANY
color processes that use three color black and white separation negatives?
Twenty years ago, I was all set to try this, but the turns of life
prevented this and the source of the Carbro materials that was available
from someone in Indiana is no more. Kodak's dropped Dye Transfer.
If I"m not mistaken, the Fresson process is a similar tricolor
registration system where the primary colors are combined. There's been
mention of the Fresson process here.

                        Thanks everyone!

                                                Rich Lahrson
                                                tripspud@hooked.net



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