imagesetter on regular sheet film?

[Jerry Cunningham]

Sir:
I know that imagesetters use lith films, but is it possible to use regular sheet film? Somewhat along the line of a film recorder? Must lith films always be used for contact printing rather than through an enlarger?
Sincerely,
Jerry Cunningham

[Eirik Berger]

Hehe, I really dont know (excuse my bad english). The idea sounds interesting, I have for several years searched for ways to make really large neagtives for gum bichromate printing. There are a copple of things that worries me about this aproach, I have worked at an offset-printer for almost 10 years, so I have some experience with imagesetters.

If this should work (I dont know if it does) with regular sheet film the imagesetter have to use "diamond screening" (FM-screening) and not conventional screening (AM-screening) which most of them use. If it uses conv. screening you will get best result with graphic lith film anyway. I have used this method some times, but I was not happy about the finished gum bichromate print. The screens (small dots on print) were clearly visible even if I used the finest screening avaliable. Do a google search on diamond-, stochastic- and/or FM-screening and you will find some information about the subject.

Another thing that may be a problem is that imagesetters use monochrome light (laser) to expose film. That may cause some surprises when developing the film. Different films responds differently on red/purple light.

The third (potential) problem is feeding the film. Most imagesetters uses rolls of film and have a cutter mechanism. You also need an imagesetter with pick-up cassette for the film instead for a online developer.

[Donald Qualls]

The other issue (beyond those already raised) that will likely arise is that conventional sheet film is much faster than the ortho lith film normally used, and can't be handled under safelight. That means that the imagesetter's exposing light may be bright enough to cause halation (robbing resolution), it'll be a bear to load (in total darkness) compared to normal safelight operation, and there's a possibility of internal systems designed for use with ortho film (such as optical film sensors operating on visible red LEDs) that will fog panchromatic film.

Still, if you have access to an imagesetter with suitable feed systems to handle sheets and not automatically develop them in the 'setter's ortho film developer, it's probably worth expending a few sheets to try it.

No, lith films do not need to be used only for contact printing -- thirty-some years ago I recall making enlarged interpositives and then contact negatives for posterization using Kodalith for both steps. Lith film is/was similar in speed to 1970s vintage Polycontrast paper, and works fine under an enlarger.

[Christian Nze]

I though that image setter use red sensitive film as they use the red laser beam. and the last time I visit my service bureau the agfa film set that it was sensitive to red. SO it should normally work on panchrofilm but not on orthofilm.

[Mike Davis]

I worked in Printing and magazine production for a while. One option that I can think of is to print on normal imagesetter film but to use stochastic screening. A stochastic job lacks a regular pattern and is similar to continuous tone on an inkjet. I'm not sure who produces stochastic software these days when I was doing it (around 95 or so) it was with test software put out by AGFA for their imagesetters. Once the pressmen got used to the idea of things being different the results were really good. Art Directors loved the lack of a pattern in their jobs.

[steve simmons]

Why do you want to do this. Why not use a film recorder. This is the accepted procedure.

steve simmons

[Janko Belaj]

Jerry (sorry for my clumsy english), what will be the purpose of such experiment? I don't see reason for playing (and messing) with panchromatic film in imagesetter (I think that panchro will be that "regular sheet film"). As first, there is usually huge problem of loading film, then - where will you find that really big film? Than - how will you shorten exposure time of your beam? I want to do such think, my coworkers will kill me. That means stopping the ordinary process, creating workflow for my crazy idea and than, later, recalibrating for normal workflow. And, at the end, what will you get out of that experiment? Laser beam is in YES or NO position. In computer-imagesetter workflow, we are getting grayscale tones with illusions. In photography on panchromatic film we have gray tone, but here we have black or white. Plus some "unwanted" effects as are fog, halo... the second in microscopic dimensions - I assume that you are not planning to enlarge negative from, let say B1 size... or? ;-))
Oh yes, please don't think that I want to discourage you, I just don't see the point. Specially in that last - "tones" question.
(and, just for info - there are also imagesetters with blue light...)



Janko