Halftoning

[BetterSense]

I want to try making photo-etchings with infinite-contrast photoresist. To get continuous-tone results I think I will have to expose my continuous-tone negative onto the photoresist with some kind of halftoning process. I don't know where to start. Can I just hold a window-screen a few mm above the easel when I go to print? It seems to be a lithographic process I don't see discussed much. Has anyone tried to make printing plates from continuous-tone negatives? It would seem to be a similar process. Do I need a special screen?

[Jac@stafford.net]

May I ask why you want to use photoresist with its special lighting requirements rather than a high resolution film?

By 'infinite-contrast' you mean strictly black and white, correct? You can FAPP do that with available process films.

[smithdoor]

Halftone is use for printing It is done by High contrast Film/Developer and using a contact screen 30 years they had a halftone film that did not need a screen. Note photoshop has this Filter some have use just a screen from a window (I have never try this but looks good too) . I have use both contact screen and photoshop.

Dave

I want to try making photo-etchings with infinite-contrast photoresist. To get continuous-tone results I think I will have to expose my continuous-tone negative onto the photoresist with some kind of halftoning process. I don't know where to start. Can I just hold a window-screen a few mm above the easel when I go to print? It seems to be a lithographic process I don't see discussed much. Has anyone tried to make printing plates from continuous-tone negatives? It would seem to be a similar process. Do I need a special screen?

[BetterSense]

The photoresist will be applied to the substrate which is to be etched. It's a necessary element. However, it may make sense to generate a halftone image on litho film then contact-print that to the photoresist. How can I generate such a halftone negative?

[Jac@stafford.net]

The photoresist will be applied to the substrate which is to be etched. It's a necessary element.

Why photoresist? What can it accomplish that cannot be done with conventional methods?

[smithdoor]

Try looking at screen printing they still have to do it the old way. I use a Process/copying camera 25 years ago.
The easy way if the still make the film today I use photoshop.

The photoresist will be applied to the substrate which is to be etched. It's a necessary element. However, it may make sense to generate a halftone image on litho film then contact-print that to the photoresist. How can I generate such a halftone negative?

[BetterSense]

Photoresist is the conventional method. What other etching method is there (besides direct laser etching)?

[Jac@stafford.net]

Photoresist is the conventional method. What other etching method is there (besides direct laser etching)?

Conventional method for what other than electronics plates, making masks for further etching, counterfeiting (poorly) etc? More specifically, of what use it in large format photography? What kind of resolution do you wish to achieve? Dot (or other shaped) halftones are rather low quality. Stochastic halftones (AKA: FM) can support higher frequency/quality, however possibly not as high quality as you need or wish.

But before going further, it would be good to know what you wish to do so we don't waste time on the impossible or irrelevant.

[BetterSense]

I want to try making photo-etchings with infinite-contrast photoresist. To get continuous-tone results I think I will have to expose my continuous-tone negative onto the photoresist with some kind of halftoning process. I don't know where to start

I don't know anything about halftone processes so I cannot give a step by step description of "what I want to do" or I wouldn't need help in the first place. Perhaps it was a waste of time asking for help, and I shall just go re-invent halftoning (poorly) by myself. Or, somebody could direct me to some resources relevant to the practicalities of making halftone reproductions; that would be swell.

[Jac@stafford.net]

Just like etching PC boards, only I want to approximate a continuous-tone image, and as you know, photoresists are not a continuous-tone medium. I don't know anything about halftone processes so I cannot give a step by step description of "what I want to do" or I wouldn't need help in the first place. Perhaps it was a waste of time asking for help, and I shall just go re-invent halftoning (poorly) by myself.

My favorite, perhaps dated source is Dan Burkholder's information on making digital negatives. He has a great explanation of how halftones of various kinds are made both traditionally and digitally. Begin here. I do not know if making a digital negative can transfer seamlessly into etching a plate (gravure process.) Lithography might be better. Good luck. Remember: Stochastic halftones.