You can calculate exposure times for F-numbers
other than given in the table above.
Suggest your lens opening is F5.6 and the table suggests F2.8
Divide 5.6 by 2.8 and square the result
In reality: 5.6:2.8 = 2 2x2 = 4 Means you
have to expose 4 times longer!
Movement of the moon is calculated:
(if you are exposing without an equatorial telescope mounting)
(Focal length of normal lens) / Focal lenght of tele lens) x 10 =
maximum exposure of Moon to stay sharp!
In reality: Tele of 400mm
( 50 : 400) = 0.125 0.125 x10 = 1.25 Seconds maximum exposure
