Re: curves and gum and Christopher James book

[Jacek <gonsaj@iinet.net.au>]

Yves, 

Maybe i'm missing your point Yves; What are you printing? Gum , Silver, Cyanotype? In my mind (not that i've done it), is use a densitometer in regards to tone mapping for silver prints. Say I take a Stouffer step wedge and contact print that on Silver paper such as Ilford Multigrade. Then I would find all the values from the deepest blacks  to the highlighted whites with a densitometer from the contact printed step wedge. 

You'd then need to make a digital negative of a step wedge or whatever variation of 0 - 100% or 0 to 255 values.
Then contact print that digital negative on the silver paper. (Using the same proccess to develop, fix, wash etc as before)
Use the densitometer to read those values on the paper.

Then correlate the contacted digital step wedge values with the contacted stouffer step wedge values, therefore resulting in a curve. You'd get rid of the process of using a scanner. There was a fellow on the web who had all the K values of what each percentage would equate to what sort of DMAX you would get on the paper. 
Though people have used scanners in this instance of a densitometer and found that its almost the same thing...
Just my two cents not sure if i'm helping you out here...
Cheers
Jacek







 On Tue Mar 11 23:15 , Yves Gauvreau <gauvreau-yves@cgocable.ca> sent:

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>Dan,
> 
>correct me if I'm wrong, but the way I interpret 
>what you say below, is because of many other factors the uglyness of the curve 
>effect is burried or hidden to ones eye.
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>If it's the case then I can understand why you all 
>have no time to waste on this. 
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>It comes back to what I said before, either 
>something or your tweeking that is hidding this adverse effect and it's not 
>the method of making the negative.
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>Regards,
>Yves
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>
>  ----- Original Message ----- 
>  From: 
>  Dan Burkholder 
>  To: alt-photo-process-l@usask.ca 
>  
>  Sent: Tuesday, March 11, 2008 7:44 
>  AM
>  Subject: Re: curves and gum and 
>  Christopher James book
>  
>Ah, we finally hear what's really bugging Yves about the 
>  curves. He's disturbed at how the curved image looks. Please keep in mind that 
>  any "profiling" is bending color and contrast. It's just that when you have 
>  the luxury of choosing a "3800 Enhanced Mat" profile for a color print, the 
>  dirty work of that bending and changing is done behind the scenes, away from 
>  prying eyes. One could liken it to observing a corpse at a funeral and saying, 
>  "my, doesn't he look alive." Were you to have an honest discussion with the 
>  mortician, you might not enjoy hearing about the cardboard forms jammed in the 
>  mouth, the cotton under the eyelids and the plugs in the ears. But if that's 
>  what it takes to make for a pretty body, why should we care? Our "curving" is 
>  just like that. Sure, we're bending tones, but when you have tens of thousands 
>  of tones to futz with in a 16-bit image and you don't see any evidence of 
>  problems in the final print, why the dickens should we fixate on the curving? 
>  That's time better spent shooting or making prints.
>  
>  In the 16 years I've been making digital negs I've witnessed an evolution 
>  in the ability of the average photographer to grasp curves. For most people 
>  who've been immersed in digital imaging for a while, tweaking a digital neg 
>  curve is no more "trial and error" than using curves on the image itself as 
>  part of the post processing. I tell students that if you learn 
>  Curves and Masks, there's a lot of Photoshop you DON'T have to learn. My 
>  personal feeling is that about 70 percent of our image-editing power resides 
>  in those two controls so learning how to finesse a curve, whether for a print 
>  or for a digital neg, is a skill that will serve you well for the rest of your 
>  photographic career now that photography is digital.
>  
>  Speaking of printing, right now I'm going back into the darkroom to print 
>  platinum. And the 3800 negs (on InkPress Transparency Film) are printing 
>  beautifully. Yes, the Curve that is applied did make the image look like hell 
>  on the computer monitor. But when I finish the print with gold and varnish 
>  later today, I'll stand back and say, "my, doesn't that print look 
>  alive."
>  
>  Dan
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>  On Mar 11, 2008, at 2:59 AM, Yves Gauvreau wrote:
>  The 
>    question that come to my mind is why a print that transformes your original 
>    in a very similar fashion as above become something that everyone seems 
>    happy about? Do you all accept these limitations as part of doing 
>    alt-prints?
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>  info@DanBurkholder.com
>  www.DanBurkholder.com
>  = 
>