Thank you for your help PE
I was thinking that if you try to expose a glass plate, coated with liquid emulsion without any filter, the results would be really contrasty. But if you use multicontrast filter ( for example filter no1) in front of the lens, would that help with the contrast? Way to predict the correct exposure time will be hard, of course..
Well, if you do that it would probably work but if you made it pan sensitive it would no longer work.
Hmm.. I'm trying to clear this dilemma in my head. So,using the liquid emulsion as a glass-plate negative with variable contrast properties,you might be able to alter it using appropriate filter. you could basically contol the contrast. But if you introduce the red sensitization, you interfere with the blue/green emulsion sensitization? Would there be filter combination to combine these 3 in the "same level" of contrast.. Hmm..
I have understood that then you are dealing with variable grade paper, there are multiple layers of color sensitive emulsion (blue and green) on top of each other. Wondering how do they combine them and keep them in harmony using it in liquid form without interfering each other.. Must be the infusion of sensitizing dye in the silver molecule before they are mixed together.
Thank you for the suggestion. I can get Panchromatic negative material. But what I really need is an Panchromatic emulsion.
You need an un-sensitized liquid emulsion (or a a slightly sensitized one if that has been done to gain speed) and add spectral sensitizers.
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Yes, i know that also. read my comment #21
At #21 you speak about modifying a variable-contrast emulsion. I have it about modifying a fixed grade emulsion.
The reason that i would need a panchromatic emulsion is that i´m trying to reconstruct Autochrome plate process for my own project. with some research and experimentation, I have been able to remedy some obstacles regarding the pitch, potato grain, lamination & sealer assemblies. I am aware that somebody has done this before using Estar etc. medium as a film base, but i am interested using a glass negative.
Now we´re talking :0)
Originally Posted by AgX
I was thinking the same thing. But if you add green & red sensitizer to fixed grade emulsion, why cannot you use the variable grade,it already contains the blue and green..? is the contrast range too big between these sensitizers..?
I made some dry plate glass negatives once with Rollei Black Magic (RBM) emulsion. See:
RBM is available in 3 different emulsions, two graded and onevariable contrast emulsion. There is also gelatine, etc. from Black Magic for coating undergrouds, etc.
Tech info & How To, click here (also about how to modify gradation, ...).
Among others, also available at macodirect.de
What type of Safelight is suitable:
* RBM23: red or yellow green
* RBM33: red or light brown, no yellow green
I hope this helps ...
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