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

Yves

You are still missing the point.

Gum printing is so flexible that you do not need fancy numbers. Making a
negative on 90 gsm Fabriabo Liscia straight from an inverted and flipped image
that looks good on the screen, will make a perfectly good gum print. i am
afraid that Sandy has rather distorted what I have said. Curves did confuse the
issue in this context as it would have been easier to have made the point, as I
did, by making the analogy with the stretching of tones in a silver gelatine
print from a weak negative, ie on hard paper..

Of course you need to adjust the curve for platinum printing when using
digital negatives.. I have had a very useful discussion on these matters with
Dan at 0230 in the Macdonalds at Gatwick airport..

i have my digital cameras and my scanners and I use them. I also use wet
processing. it just so happens that I get a great deal of pleasure, on many
levels, from taking photographs for platinum printing on my 10 x 8 camera,
exposing and developing those negatives to meet a density range for platinum ( a
platinum curve !) It is also my view that these special in camera negatives
produce better platinum prints on a side by side comparison with prints made
from digital negatives.. (You may care to have a look at my articles in View
Camera).

Puyo and Demarchy are two of the greatest gum printers . Please have a look
at their work in the archives of the Societee Francaise de Photographie in
Paris and read their articles in the annuals of the Society around 1900.. Also
have a word with your compatriot Christian Nze who contributes to the discussions
on Dick Sullivan's discussion list which is accessible through the B & S web
site. Dick is quite strict in ensuring a high level of discussion. The point
is that Demarchy and Puyo produced gum prints with an apparent large range of
tone without multiple printing. I have the annuals for the years concerned. I
meant to read them last night, I have set, but got involved in some research
on Ruskin's use of the daguerreotype instead.

All the best

Terry

In a message dated 3/5/06 8:29:50 am, gauvreau-yves@sympatico.ca writes:

>
> 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 05/03/06-02:18:41 AM Z