Numerically, 1/100 inch at 12–15 inches is closer to two minutes of arc. This choice of CoC limit remains (for a large print) the most widely used even today. takes a similar approach based on a visual acuity of one minute of arc, and chooses a circle of confusion of 0.025 cm for viewing at 40–50 cm, essentially making the same factor-of-two error in metric units. It is unclear whether Abney or Dallmeyer was earlier to set the CoC standard thereby.
Numerically 1/100 inch at 12–15 inches is closer to two minutes of arc This choice of CoC limit remains (for a large print) the most widely used even today takes a similar approach based on a visual acuity of one minute of arc and chooses a circle of confusion of 0025 cm for viewing at 40–50 cm essentially making the same factor-of-two error in metric units It is unclear whether Abney or Dallmeyer was earlier to set the CoC standard thereby