Additive vs Subtractive

It was me… Sorry, I should not have done that; it seeds confusion.
That name `Agfacolor-Old´ (Agfacolor-Alt) was not at all an official name but is used sometimes in Germany to distinguish that additive grain grid film from the newer chromogenic substractive three-layer film:

1916
Agfa releases a color plate `Agfa-Farbenplatte´ similar to the Lumiere Autochrome plate (resin in place of starch grains, no soot filled inter-grain space, as those resin grains are flattened out after coating getting them into contact at full circumference; thus more speed gain, higher resolution; could be that the grains themselves were smaller too)

1932
A similar coating is done on film base (sheet and roll-fil)(35mm only in 1935). These films are called `Agfacolor´, and the glass plate Farbenplatte also gets this new name.
To make things even more confusing (it’s not me this time…) Agfa releases the same year another type of additve material: their lens grid film. (for Contax and Leica cameras with 3colour stripe filters on apt lenses) This film is called Agfacolor too…

Thus additive grain grid films and plates and an additive lens grid film bear the same name.

1936
And then their subtractive chromogenic three-layer film is released. Yes, as you would expect, called Agfacolor… To make things a bit more clear it was called in the beginning `Agfacolor-Neu´.

Junior said:

Okay, I think I'm getting a little confused here now after the reference to printing via pigments

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Junior,

It’s a pity that your first post is caused because you’re in despair…

But I think it is not me to blame but that whole subject is really complicated. Yes, as you I learned those models of subtractive and additive image capture and realease.

But it is best just to regard them as models, nothing more.


As indicated when referring to mechanically printed subtractive images that model of staggered subtractive filters is not totally matched when you look at those spots of dyes. Even less match to that model you will get when that subtracrive print is made with the use of solid, totally opake pigments.
I remember that R.W. G. Hunt has wrote something about that. Also have a look at the theories of Harald Küppers. Perhaps you could find something in his books which makes you feel at ease again.

I guess, that those materials still work according to those models, could be tried to be explained by reflections within the coating and the low resolution of our eyes.


A hexachrome system as you refered to, is used (to my understanding) to compensate for shortcomings in the absorbtion of the inks previously used. Within the ideal scope of colours to be produces such a system would yield a larger area. Again Küppers would be a good reading, he advocates an octachrome system.(Dead Link Removed, but I rather prefer his books above that site)

To make things even worse there is someome as Edwin Land with his very own theory…


As in life in general putting things into drawers is not always applicable, sometimes they get stuck, sometime one has to relabel them. But they make life so much easier.

Hello All,

First I'd like to thank PE for a great response. I heard that familiar "click" in my head as I read...things are coming back en masse!

In addition, AgX, please don't feel that I was indicting you in any way or that you caused me inordinate grief; had you not posted what you did, I'd have gone on in ignorance. It wasn't your post that left me wanting for knowledge, but my own forgetfulness. I'm very glad to read any and all posts--they all make me think more, which is a good thing.

Finally, my intention was not to turn this into a forum for anything other than analog photo discussion (not commercial or other printing topics). It's just that I became interested in analog photography after I had to learn some fundamentals about darkrooms while I learned about the flexo printing industry. If I reference that experience in the future, please understand that this functions as part of my basis for underatanding color and light.

Best,

Junior

I don't see why one/we should not refer to these other topics as they are strongly connected to photography and further are important to our understanding (or are undermining our understanding...) of those models we are talking about.

Lee L said:

... It's also interesting to note that I got very long exposure times when printing with Cibachrome materials using the PCS-150 adapted to an Omega D5 condenser head....

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Do you have a speculation as to why your exposure times were unexpectedly long with Cibachrome?

MMfoto said:

Do you have a speculation as to why your exposure times were unexpectedly long with Cibachrome?

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Not having done any real research, I'd expect some combination of two factors. The 50 nm passbands on the RGB dichroic filters in the PCS-150 could be better matched to the peak spectral response of Type C materials than the 1986 vintage Ciba materials I was using, and the fact that Ciba materials were slower to start with. I was using the more expensive glossy materials, and can't recall the speed of the pearl type finish materials, or if it was different. This was all before RA4 materials were introduced. I do have a couple of Cibas from then that have almost the quality of the current Kodak metallic type papers in both spring green trees and a red painted swing seat.

As I recall, the times for 6x9 inches with Ciba were in the 90-120 second range.

Come to think of it, most of this Ciba printing was from Kodachrome, mostly 25, which may also have contributed to the longer times. I also printed some with the Agfachrome slide printing material that was out briefly, and which felt a bit like printing on film. I don't recall the printing times for that well, it was about '82-'84, but I believe the times were pretty short.

I haven't seen numbers or a chart for the passbands on the PCS-150 filters, just the 50 nm bandwidth number in the Philips Darkroom Book by Peter Charpentier published in Amsterdam/Brussels in 1983 (which I found a year ago at Half-Price Books, apparently used from someone's personal library).

Lee