User blog:Angrybirdstd/Extent of Enhanced Eyesight

There is a such thing as enhanced eyesight, but there are different branches of it, too.

Branches
Look at the vision articles on the SP Wiki for all other powers. These ones are not listed.
 * Visual Acuity
 * Color Vision
 * Contrast Rensitivity
 * Frame Rate

Visual Acuity
Visual acuity is the power of a being to resolve small details, like the small E on the Snellen eye chart. It is measured using a fraction with 20 as the numerator. The larger the denominator, the worse the eyesight. The actual acuity is an angle. 20/20 corresponds to detail subtending 1 minute of arc (1/60 degree), while 20/1 corresponds to detail subtending 3 seconds of arc (1/20 minute or 1/1200 degree). It is measured using a faraway chart with letters progressively decreasing in size. At an optometrist's office, if the patient cannot resolve the detail in the huge E at the top of the chart (20/200 or 10 arcminutes), he will be pitched against a distance test called Counting Fingers.

Counting Fingers
Count Fingers is measured in CF x (x is the farthest the patient can count fingers in feet) and is used for testing people worse than 20/200 (10 arcmin)
 * CF 20 = 20/400 or 20 arcmin
 * CF 10 = 20/800 or 40 arcmin
 * CF 8 = 20/1000 or 50 arcmin
 * CF 7 = 20/1143 or 57 arcmin
 * CF 6 = 20/1333 or 1.11 degree (67 arcmin)
 * CF 5 = 20/1600 or 1.3 degree
 * CF 4 = 20/2000 or 1.7 degree
 * CF 3 = 20/2667 or 2.2 degree
 * CF 2 = 20/4000 or 3.3 degree
 * CF 1.5 = 20/5332 or 4.4 degree
 * CF 1 = 20/8000 or 6.7 degree
 * CF .5 = 20/16000 or 8.9 degree

Eye Chart

 * Line 1 (E) = 20/200 or 10 arcmin
 * Line 2 (FP) = 20/100 or 5 arcmin
 * Line 3 (TOZ) = 20/70 or 3.5 arcmin
 * Line 4 (LPED) = 20/50 or 2.5 arcmin
 * Line 5 (PECFD) = 20/40 or 2 arcmin
 * Line 6 (EDFCZP) = 20/30 or 1.5 arcmin
 * Line 7 (FELOPZD) = 20/25 or 1.25 arcmin
 * Line 8 (DEFPOTEC) = 20/20 or 1 arcmin (60 arcsec)
 * Line 9 (LEFOPCT) = 20/15 or 45 arcsec
 * Line 10 (FDPLTCEO) = 20/13 or 39 arcsec
 * Line 11 (PEZOLCFTD) = 20/10 or 30 arcsec

How to go Farther than Eyechart
Just snip the 20/10 (last line) line off the chart and put it farther from you.
 * 11 at 6 meters (20 ft) = 20/10 or 30 arcsec
 * 11 at 7.5 meters = 20/8 or 24 arcsec
 * 11 at 10 meters = 20/6 or 18 arcsec
 * 11 at 12 meters = 20/5 or 15 arcsec
 * 11 at 20 meters = 20/3 or 9 arcsec
 * 11 at 30 meters = 20/2 or 6 arcsec
 * 11 at 60 meters = 20/1 or 3 arcsec
 * 11 at 90 meters = 20/.75 or 2.25 arcsec
 * 11 at 120 meters = 20/.5 or 1.5 arcsec
 * 11 at 150 meters = 20/.4 or 1.2 arcsec
 * 11 at 180 meters = 20/.33 or 1 arcsec (1000 arcms or millisecond of arc)
 * 11 at 300 meters = 20/.2 or 600 arcms