Some PDF renderers "enhance" thin lines, i.e. make them thick enough to be clearly visible, no matter how far one zooms out. Other PDF renderers do not artificially thicken thin lines.
Adobe Acrobat Reader allows one to choose between these two behaviors via an item in the application preferences.
The Preview application always enhances thin lines, and does not seem to provide an option to suppress this behavior.
Is there some hidden setting on the Mac which will prevent thin lines from being enhanced? (e.g. "defaults write ... ")