To some degree it depends on your vision. The 264 PPI is about my resolution limit. My boss probably couldn't tell the difference with more than 100PPI. I shou

To some degree it depends on your vision. The 264 PPI is about my resolution limit. My boss probably couldn't tell the difference with more than 100PPI. I should be able to tell you the theoretical diffraction limit based on a 5mm pupil at 18", but unfortunately...