Post by mistervista on Apr 10, 2014 15:05:44 GMT -5
I have an Asteria 150mm F8 R35 with a Chromatic Abberation Ratio of 1.83
To achieve the Standard Sidgwick CA Ratio >3 for planets at high power with 6" aperture this worked perfectly and fits like a glove
1. A Coleman Propane Lantern Replacement Base (attached).
2. The Math - A 6" F18 will have a CA ratio of 3
My 48" Focal Length divided by a 4.6" aperture mask = 10.43 x 1.35 R35 = 14.08 FL divide by 4.6 diameter again = 3.06 CA Ratio
3. Do the math for your focal length whether Achromat or Asteria (x 1.35) then use a Router, Dremel or metal file to create the proper mask hole diameter then slide it in the Dew Shield.
To achieve the Standard Sidgwick CA Ratio >3 for planets at high power with 6" aperture this worked perfectly and fits like a glove
1. A Coleman Propane Lantern Replacement Base (attached).
2. The Math - A 6" F18 will have a CA ratio of 3
My 48" Focal Length divided by a 4.6" aperture mask = 10.43 x 1.35 R35 = 14.08 FL divide by 4.6 diameter again = 3.06 CA Ratio
3. Do the math for your focal length whether Achromat or Asteria (x 1.35) then use a Router, Dremel or metal file to create the proper mask hole diameter then slide it in the Dew Shield.
