What resolution ?
For pixel based files — (TIF, JPG, PNG, PSD) —
Traditional press printing (magazine, brochures, greeting cards) — 300dpi
Larger format for up close viewing – map, high quality photos and posters — 150 dpi
Banners and signs — 100dpi to 25dpi. What !? 25 dpi?? — Yes, large road signs are printed at this
resolution and lower and look perfect. If you were to stand close to these large graphics, the pixels would be terribly noticeable.
Vectors (text, shapes, lines, logos )— are resolution independent, so no need to worry about it. A small vector logo on a business card will print at perfect quality 100 feet long. Vectors are not made up of pixels.
Should I up-res my small file to a big one?
No, Photoshop averages from existing pixels. No new data is created, only averaging from existing data, so the prints go from few big pixels to many small pixels. Said another way — up-resing from pixelated to blurry. We say leave it alone.
PDFs, PSDs, and all native application files can have both vectors and pixel based files, so knowing that the file is a pdf for example does not tell you what is inside it.
Most all files we receive these days are PDFs. Depending on your application choose – high quality printing, and downsampling off. This is now the default in most applications. The quick answer is — wherever it asks ‘ok to make this___ change? answer: no, don’t touch. We want the file that is closest to your original file.