Diagonal OffAxis Illumination Calculator 

Unit of measurement:  inches millimeters 
Mirror diameter =  
Mirror focal length =  
Diagonal to focal plane distance =  
Eyepiece field diameter =  
Diagonal sizes (m.a.) to select from =  
Acceptable magnitude loss =  

Diagonal size minimizing obstruction =  
Diagonal size maximizing illumination integrated across the field =  
Diagonal size for most even illumination across the field =  
Diagonal offset towards primary mirror and away from focuser = 