D A W E S    L I M I T 
Tom  Whitney     256-6234       E-Mail
Dawes Limit Max. Resolving Power of a Scope
Resolving Power Spatial Resolution ability of Scope
      to distinguish Points affected by -
     Aberration  Shape & Quality of Optics
     Diffraction - Wave Nature of Light determined by Aperture
                            Creates Airy Pattern - Ring Diffraction Pattern
2 points are Resolved if Principal Diffraction of  pt.1 is grater
     distance from Minimal Diffraction of pt. 2
Metric Dawes Limit
      Centimeter Aperture divided by 11.6 = Arcseconds
American Dawes Limit
      Inches Aperture divided by 4.56  = Arcseconds

Link - Calculate Dawes Limit