distance perspective

[Rodger 527]

Does anybody know a rule of thumb to simulate distance when reading a sign . I have read the letter size recomendation for distance , but want to see what the shadows , outline etc look like at a distance instead of close up ( on my moniter ) . I am making a 2' X 4' sign to put at a livestock auction ring with the seats being from 30' away to 60' away . I am guessing to measure what the signs measurement " looks " like at the 60' mark & make the sign that big on my moniter   I like some of my designs close up , but when I decrease the view , they become garbled . Thanks for any input .