I have read people writing on this forum that the maximum possible field of view in a 1 1/4" diameter eyepiece is 1.33 degrees. However, I also read people writing that they get FOVs above 3 degrees with low power 1 1/4" eyepieces in short focal ratio scopes. If both these statements are correct, can someone reconcile them for me?
FOV Question
Started by stuper1, 05/03/2003 01:36PM
Posted 05/03/2003 01:36PM
Opening Post
Posted 05/03/2003 01:55PM
#1
afov(actual fov) is determined by objective focal lenght and the fied stop diameter of the eyepiece. In an 1.25" eyepiece, the largest size of the field stop is somewhere around 24mm, maybe 24.5. The formula for determing afov is
field stop(mm)/Objective FL * 57.3
for a 1000mm lens it is around 1.4*
for a 500mm lens it is 2.8*
I suspect someone was referring to a scope with 1000mm FL when stating the 1.33 degree max.
Walt
field stop(mm)/Objective FL * 57.3
for a 1000mm lens it is around 1.4*
for a 500mm lens it is 2.8*
I suspect someone was referring to a scope with 1000mm FL when stating the 1.33 degree max.
Walt
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