About the number of limit seconds of composite in planet photography 
with the optical resolution limits of the telescope.
I made calculation types such as the following.

The number of limit seconds.(It is stricter than the theory value.)
D=Telescope Diameters (cm)
dia=The diameters of the appearance of the planet(")
h = The hour number of times which  the planet One rotating of necessity 

Limit seconds = h * 8000 / dia" / D(cm) 

Example
Jupiter   10 hours  , 45" , 31cm
limit seconds =10 * 8000 / 45 / 31 = 57(sec)

Mars     24.6 hours , 15" , 31cm 
limit seconds =24.6 * 8000 / 15 / 31 = 423(sec) .. 7minutes
 

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