Question for 1/2 tone problems

[woodrow]

Good Day everyone, I want to make an attempt to learn photoshop or at least a good basic foundation for understanding its functions...Being a printer for many years I understand the physical aspect but now I'm trying to resolve some issues between departments (screen/art). Here's what I'm not understanding from the Art side, when they create the 1/2 tones the burnroom brings positives to me and tell me the tones are too small for the particular mesh, this I understand but when they adjust the curve and bring them up there are still 1/2 tones they do not see unless they zoom in which they either don't like to do or it takes too much time. So what I asked was there a way to adjust photoshop that wouldn't allow or at least flag an issue with compatibility tone to thread when they are creating a piece?? We are in the testing stages of using 305 mesh but I'm going to try that on static frames because of fact we have MHM's and expresses. Finer mesh resolves the problem but the company is not at this point giving up the massive screen inventory, I understand this as well...if anyone could point me in the right direction or advice I'd be most appreciative... Thank you!

[blue moon]

not really sure I follow the question, but my first thought would be to decrease the lpi to get bigger dots. Going into curves will make changes to the image and is not usually what is done to make the films work with thicker mesh.

What mesh are your screens? What kind of condition are they in?

Have you done a test to see which halftones you can hold? If you run a ramp from 0-100% at what point the you lose it?

pierre

[Frog]

What lpi is being used on the problem films? And, as Pierre asked, what mesh were you trying on these?

What is the tonal range, and are you only having issues with the two extremes?

[woodrow]

We've been sticking to primarily a 50 lpi and the mesh ranges are from 120-260, nothing below a 7% across the board but they often go as far as they can (1%) when they make the adjustment to bring it up to 7% those smaller percentages do not show up. From what I'm understanding it's the rip that needs to be managed with the subset tone curves to eliminate them from ever being put to film.One artist has finally managed somehow to manipulate this curve but the spacing of the dots to where they are spaced properly is his issue. If it helps we have harlequin RIP...

[Frog]

Well, as you may have heard in the past, to avoid or at least minimize moire interference, most folks shoot for meshes between 4.5 and 5 times the lpi (or vice versa)
So, if all of your art is using 50lpi, your mesh should never be coarser than 225 (230 is common)

[screenxpress]

When I read 50 lpi and 120, out loud I uttered OMG!  Ask my wife.

As Andy indicated, 4.5 (better at 5) times lpi to mesh. 

Not surprised the dots were falling through the holes 

Adjust the lpi, not the curves.  Adjusting the curves will make some of the lighter areas darker (denser), but the remaining lighter areas will still produce sparse dots and.................

[Admiral]

These guys already answered it but I just want to add to it a bit.

It probably won't help you at all, but on thin thread mesh counts, higher LPI's do work.  I've done 50LPI on 150S, decent amount of 55LPI on 225S, and I saw at a trade show but I wouldn't bother doing a 55LPI on 150S.

Thin thread mesh counts are a bit of an exception to the rule but being at least at LPI x 4-5 to get the minimum mesh count for it is a good idea.

[blue moon]

When I read 50 lpi and 120, out loud I uttered OMG!  Ask my wife.

As Andy indicated, 4.5 (better at 5) times lpi to mesh. 

Not surprised the dots were falling through the holes 

Adjust the lpi, not the curves.  Adjusting the curves will make some of the lighter areas darker (denser), but the remaining lighter areas will still produce sparse dots and.................

this!

also, print some test patterns  (0-100% gradients) in different lpi's and burn them onto the screens. You'll know what you can hold. It will take out a lot of guessing for the art ppl.

pierre