Re: Sources for stochastic screens
Well, Jon, I have a funny--last night I checked out Keith Taylor's aquatint screen source, Elizabeth Dove. Come to find out she lives in MT! And teaches at U of M! Our rival :) So I ordered one last night, and even funnier, she emailed back and said, "This is weird, on a friday night I get two orders for these screens, which I don't get much, wonder what is going on?" The other order was from a guy in TX. I told her there was a post to the alt list about her and that Keith was a blabbermouth, heheheh. So there's one happy woman and another reason this alt list is so wonderful. I've been rereading every text I have on solarplate--Keith Howard, Eskola, Boegh, Welden/Muir (ordered the Ponsaing book Keith recommended, have had the others quite a while), and the more I do it and read the greater my understanding is growing. For instance, silly me--I thought Boegh had a particular image backwards in his book--it was of a test strip of aquatint exposures ranging from 15 sec to 90 sec, but the lighter exposure was 15 sec. This flew in the face of reason that the greater the exposure on solarplate the lighter the print, so I just assumed he did it wrong. BUT what I have since realized from rereading all books and looking at Jon's little dot diagram, is that the exposure of the screen starts OUT washed out, then gets blacker. No WONDER I had a calibrated exposure of screen to be 1mn 15 sec and couldn't figure out why I needed longer. I was looking only for where open bite disappeared, but I should have been really looking for when first max black occurs. AND when doing this with a UVBL unit, the exposures should NOT be in steps of 15 sec--too short--but in 1 minute steps up to maybe 10 minutes!! I found this in another little part in Boegh's book, a caption to a photo where it talks about relative exposures of metal halide to UVBL. Little things like this make more sense. When Keith mentioned wetness of the paper a culprit, I again found ref to the fact that blotches/uneven tones can be a result of the wetness/dryness of the paper, lack of evenness, etc., so again, no WONDER it is good to soak a long time but to let paper sit in bags. So every little bit helps on my way to perfection, short of ordering a vacuum frame. Pray for a tax refund. At least all these failures will benefit the alt process manual chapter; no better way to learn a process than to fail at it over and over again. Chris PS one last thing--when doing the Boegh and others method of clipping tones in a curve dialog box to 80%, this only works on grayscale the way he suggests--moving the point top right down to Input 100/Output80. If in RGB mode you have to move the bottom LEFT UP to Input 0/Output 50--dif numbers and dif directions. But you all already know that. I am not using this method of curving, preferring instead to build a PDN curve with no tonal clipping, but for those who want a low tech way of adjusting the image to suit a plate, this is it. ----- Original Message ----- From: "Jon Lybrook" <jon@terabear.com> To: <alt-photo-process-l@usask.ca> Sent: Saturday, February 24, 2007 10:43 AM Subject: Sources for stochastic screens I called around and found a guy here in Boulder who seems to know what he's talking about in terms of outputting an 1800 dpi 80% density stochastic screen on him imagesetter. I'm meeting with him next week to show him the screen I'm using to see if he can accurately reproduce it. He said typically they output at much higher rez natively, but can make it output at 1800.
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