Printable View
Hi All, I recently came across this 4" by 6" negative looking thing with all kin ds of calibrations on it in a camera store. It has Beta Screen co. printed on it and also spread guide, and it says avalible lines 60, 65, 85, 100, 110, 120, 13 3, 150. Can someone tell me what this is and how it is used. Thanks, David
A little hard to tell, but it might be a device used in the printing industry to determine the DPI of halftones. Those numbers you listed are the standard DPIs they use.
Back in the dark ages <g> halftones were made by placing a screen (actually a tr ansparency) over the original and photographing it on high-contrast material. Th e screen renders the reproduction as dots, large-to-small dots depending on the reproduced tone. A press can't print tones, just black and white or large-to-sma ll dots.
Halftone screens are designated by coarseness; the more lines (lpi) the finer the detail that can be rendered, but that has to be balanced against what kind o f paper the halftone will be printed on and other assorted factors.
While you can easily see the difference between a 60-line screen and a 120-lin e screen, it can be difficult to tell between say an 85-line screen and a 100-li ne-screen; what you have it the comparator you can use to determine what screen you have.
Now I've just demonstrated how obsolete I am. <g>