Re: Back-exposing on plastic (was: Re: Gum transfer

Terry,

you may be right, I thought I read posts by you quite a few times where you kind of find digi-negs a waiste of time. Below you obviously don't say this again and you basically agree with the concept of matching a negative with the process response. The way this is done, wheter the traditional approach (wet processing) or the digital approach (curves) is irrelevent, it could be much easier and much less costly to play with numbers then with chemicals but that's another story.

in an earlier message late last night you wrote this: "It is you who has fallen into the trap of allowing yourself to be blinded by this obsession with curves"

and before that, to me you wrote this :

"This was an attempt to explain the inexplicable.

The curves are not only an unnecessary complication but they also confuse the issue. Expressed without reference to curves, all this is saying is that there is a loss of gradation if the density of the print is 'stretched'.

Incidentally, how would you explain Puyo's technique in making single coat gum prints ?

Furthermore, if you think that you are not getting your point over in English, why not make the point in French too ?"

I could go on but it would be pointless IMHO. I don't know this person, Puyo's and there are a lot more things I don't know about or don't understand but if I would have a little bit of context on what he does I'm sure if not me, someone else could give you all the response you want and maybe much more.

But if I was satisfied with a relatively low Dmax, say the 1.2 as Sandy said earlier and the relatively flat response obtainable from a single coat gum print. I would approach the problem this way, first I would make enough gum emultion such that can make quite a few test and prints without changing anything to my recipe. One of my first test would be to find how much exposure I need to secure the target Dmax. The next test would be to print a standard step tablet to learn the response of this particular emultion/paper combo if not already done simultaniously in the exposure test. Now I don't presuppose a linear response would suit the image just like that and I would use a negative feedback approach to find what kind of curve I will use for this image on this particular emultion. The way this would be done is say I print a negative where the densities progress in a strait line from min to max and to compare it with a different version, I could begin by increasing the contrast in the highlights, if I don't like that I could try the same with the shadow and so on until I'm satisfied I've made the finest print I could.

Now I claimed not long ago that I could manipulate the negative values to produce any tones or densities I wanted from the min to the max a specific emultion can produce with proper exposure but I didn't say how and since then I've find out quite a few things. To make things as short as possible the concept is this: An (R,G,B) triplet is normaly viewed as a color, from now on, lets view it as an effective UV density.

We all know a specific density on a properly match negative will cause a distinct exposure to be effectively applied locally under the area(s) where we find those specific densities and this will cause some specific tone to be produce. Now say I can choose from 16 million such triplets each producing a specific density value but not all triplet produce a distinct density value or the other way around it is possible a specific density can be obtain using different triplets. If I would choose from this large pool of triplets a bunch, such that each of them produce the tone that I want, this would give us an incredible number of ways to print a gum emultion in a single exposure. There is however a BUG with this idea, no it is not the number of distinct density that can be produce but rather the software we are using doesn't allow us to change individual pixel value one at a time, it's crazy but they where not design that way. But thankfully, there are workaround and it wont be long before someone gets it, if you see what I mean.

Regards
Yves

PS. There are many many details I left out but be assured, we wont need to involve the NASA.

 
  ----- Original Message -----
  From: TERRYAKING@aol.com
  To: alt-photo-process-L@usask.ca
  Sent: Tuesday, May 02, 2006 8:12 PM
  Subject: Re: Back-exposing on plastic (was: Re: Gum transfer

  Yves

  There may be a language difficulty here as I do not think that you have understood the relationships.

  Each of these processes has a maximum density range that does not change. It is a constant.

  This is chemical and physical constant independent of how one makes one's negatives, Photoshop or what is done in the printing industry.

  Of course, if one has any sense, one makes one's negatives, whether digital or otherwise, to suit what each processes will accept..

  As a rider to the above, this does not mean that one has to expose a different negative for every process. Different scenes call for different processes. while negatives can be adapted to suit different processes.

  Terry

  In a message dated 3/5/06 12:37:44 am, gauvreau-yves@sympatico.ca writes:

    Terry,

    your position on the pertinence of manipulating the distribution of values on a negative in order to produce a better match between the neg and the properties of a process dependent print is well known. I don't critic your position, I just don't understand why an experience guy like you who probably as work very hard to get is negatives to match as much as possible the exposure scale and other characteristics of his print process material. Even assuming you never did made any special effort of any kind ie. use and develop his films as per the manufacturer recommendations. I'm sure you tried to bring the best out of your prefered ones amoung all these negs in some fashion or another.

    If you did any kind of change to your negatives and or chosen a different paper grade or even choose a process that would produce the best image you can do or think of. Well today, with computer program like Photoshop you can practically print any negative on any kind of paper or whatever process you can think of. This as been done for years in the printing industry, ok it's not art but the basic are exactly the same.

    Regards

    Yves

     
Received on 05/03/06-01:29:14 AM Z