I use indesign CS5 and many short lines of 0.5 point in my project.
After export to pdf (press) everything seems correct. After rip process from printer office in compressed file lines seems to have different thickness even on large zoom (400%).
High quality pdf from rip prepared by printer office still shows small differences in thickness. Lines are in one solid color in my project.
What is the source of this problem? 0.5 point ines seems not extremely thin.
If the line is not sharp in pdf will it be not sharp in press?
I wouldn't go off what I see on screen. I'd be asking the printer for a hi-res proof. If that's not satisfactory they could run a test on offcuts on another print job to see where the problem lies.
One reason for different linethickness could be that the lines are interacting with transparent areas, giving the appearance of thicker, or could be physically changing the width by a few decimals.
I'd try putting any of the thin lines on their own layer - and perhaps try different PDF compatibilities, from PDF 1.3 to PDF 1.4 etc.
Acrobat has a setting, on by default, to Enhance Thin Lines and it can really throw your screen view way off. Make a print from that PD proof.