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Roger Martin
11 Posts |
 Posted - 09/16/2009 : 06:38:22
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I have a presstek, Momentum, Harlequin, Rip. We are running a Heidi-46 DI purchased from presstek three years ago. I would like to get the screen patterns to not show as much, this pattern shows more in the cyan than any.
Thanks for any help
Roger |
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Marc Bremer
Netherlands
107 Posts |
Posted - 09/18/2009 : 11:45:57
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| How many DPI's you print (1270/2540) and what screenruling (150/175LPI) |
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Roger Martin
11 Posts |
Posted - 09/18/2009 : 12:20:24
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I am using 1270 dpi and 175lpi, if i make a screen test from the press itself the screen is smooth, but when using the presstek rip it shows an obvious pattern, this pattern can be seen even with one color at a time especially with cyan.
Roger |
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Marc Bremer
Netherlands
107 Posts |
Posted - 09/18/2009 : 13:49:09
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I have noticed myself 175 LPI and 1270 is to much (you have hps screen turned on to get enough gray values) if you turn hps screening off the moire pattern disappears but in a gradient you will notice banding, because off to few levels off gray (1270/175)^2= about 49 levels of gray
(1270/150)^2= about 72 levels of gray, still to little to print smooth gradiants. Thats why you have to use the HPS option turned on the rip wil generate extra levels of gray to print smooth gradiants. Another setting to look after is the zero degree angle correction (normally this should be the yellow color) is set to 33.33% als to avoid moire patterns |
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platetopress
5 Posts |
Posted - 02/23/2010 : 09:25:38
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| Depending on the age of the press you can probably run 1270dpi at 150 lpi without any problems. If you are using a newer press or have had the laser upgraded in the platesetter then you can probably do 1270dpi at 175 lpi. The EllipticalP dot is recommended on the DI presses, but you can also use Round if you are having a moire pattern. It is important to turn on 'Harlequin Precision Screening'. This will almost always eliminate any issues with moire if it is turned from OFF to ON. |
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Moir'e pattern in midtones
