Note 18 — Chapter VI · EYE PIECES
Reading edition
The angular field a is defined by
tan ½a = γ/F
where γ is, numerically, the radius of the field sharp enough for the purpose in hand, and F the effective focal length of the ocular.
Reading edition
The angular field a is defined by
tan ½a = γ/F
where γ is, numerically, the radius of the field sharp enough for the purpose in hand, and F the effective focal length of the ocular.