Believe it or not, it depends on paper, screening technology, and press. I've never created less than .5pt vector artwork. In your file, it may depend on the color percentages. Hard to say without seeing the artwork and your PS Color Settings. In my opnion, if the lines appear to be .5pt or thicker; you should be OK.
ok that makes me feel a bit better, I create the artwork in PS then import into Illustrator and use Illustrator to add any text and export as JPEG or PDF depending on the shop.
While it was in Illustrator, I drew a few 1pt lines over the artwork to compare some of the questionable spots and they all appeared to be .5 or thicker in weight so hopefully things will turn out well.
I regularly use .25pt for line art, sometimes even less.
But as John says, it depends, also on printer (type).
You may create a set of small paths of different shapes (rectangles, stars, ellipses, whatever) to represent different directions, and then make copies with different Stroke Weights.
You may use 1pt, .75pt, .5pt, .25pt, .2pt, .15pt, .1pt, .05pt, and compare in print, from Illustrator or from PDF, if possible with the printer for the job.
You can also see what it looks like when printed on a laser printer.
I am putting together some business cards and a portion of them is done in Photoshop.
I am worried about blurry results and would like to be sure that the graphics will print well.
Is there any way to be sure that what I see on my screen as far as photoshop graphics will print as they appear?
More specifically, I see that some lines in the artwork appear to be less that 1pt wide, can someone tell me how a line which is less than one 1pt would turn out in print?
Any help is appreciated!
If you keep the line as a vector shape and save the Photoshop file as a PDF with "photoshop compatible" checked, it should save all the vectorized information without rasterizing it. You'll get a much better print that way.