U of S | Mailing List Archive | alt-photo-process-l | Re: digital negative possibilities for gum

Re: digital negative possibilities for gum

On Oct 19, 2006, at 12:36 PM, Ender100@aol.com wrote:

Hi Charles,

The bitmap negative is one of those binary types of negatives.. it is either printing with full tone or no tone—the closer the printed dots are together, the more tone. This is why the negative appears to be more dense—because there is no continuous tone in it. It would be like an imagesetter negatives. Printing with dots is fairly foolproof, though not what I would want for PT/PD. However with full color gum, you have at least 3 printings to get a "dither" of the three colors, which will hide the dots somewhat.
But that still begs the question, why?

At any rate a bitmap that's given a curve correction doesn't look that dark. I've never tried to print an uncorrected bitmap; when I started out with bitmaps I was working from Dan's book, and the book said a bitmap needs a curve or it will print too dark, and I didn't have any reason to doubt him, so I got one of the curves off his CD and tried that and it worked pretty good, with some slight modification, and so I always used that on all the bitmap negatives I ever printed. As you can see from the other negative posted, I prefer a rather thin negative for gum; much density doesn't do anything for gum, as many people before me have pointed out.

I dug out an old bitmap laser printer negative, one for a print I've got on the website, so you can see what a correctly curved bitmap might look like. (The film it was printed on was translucent white when it was new, but over the years has faded to this ugly yellow- brown color).


I didn't get Charles' post, below, so will answer it here. Like I said, I've never tried to print an uncorrected bitmap, and to answer his question I should probably try to print this with more exposure, but I'm not going to because I can't see any reason to waste any time on bitmaps. (For this demonstration I was following Chris's protocol of using the same time for both negatives). But just looking at it, I'd just say it's just not a good negative for gum, and more exposure isn't going to help it. What I suspect is that if I printed it long enough to retain the details in the face, then the shadows would be way overexposed, and then you end up with the problem that if you develop long enough to open the shadows, you'll lose the highlights. That's what I meant when I said that the negative "prints with too much contrast."

Best Wishes,
Mark Nelson

Precision Digital Negatives - The System
PDNPrint Forum at Yahoo Groups
Military Commissions Act of 2006 - A STAIN on our Nation's History

In a message dated 10/19/06 1:08:16 PM, cryberg@comcast.net writes:

This is getting interesting. I do not (yet) do gum but it sure looks as if
the bitmap negative has the same amount of detail that the regular ink-jet
one has but that it is much more dense. Wouldn't extra exposure give a
print much like the regular one?
Charles Portland OR