So here it is:
I uploaded my picture of Saturn in WinJupos. Using the measurement - adjustment tab it's possible to obtain the diameter of the planetary disk in pixels (Di). The apparent diameter of the planet in arc seconds (Dp) is provided by ephemerides tab.
Sampling S = Dp/Di = 19/128.8 = 0.1475 arc seconds per pixel
The image sampling is equal to :
S = 206 P / F (P = pixelsize of the camera and F = effective focal length in mm)
So F = 206 P / S = 206 3.75 / 0.1475 = 5237 or F/D = 5237/200 = 26.18
Conclusion :
My set up with barlow x2, ADC and ASI224MC (3.75 micron) on TAL200K f/8.5 has an effective focal length of f/26.18. This means that my magnification is 26.18/8.5 = 3.05
Based on this f/26.18 and a Dawes resolution power (RP=1.02 wavelenght/diameter telescope) of 0.5838 it possible to measure the sampling factor k (k = RP / S).
k = RP / S = 0.5838 / 0.1475 = 3.95.
Conclusion :
The Nyquist-Shannon theorem requires a k>2 but in practice a sampling factor of 3 to 3.5 is recommended according to Christian Viladrich - Solar Astronomy page 300 - Planetary Astronomy page 80). Increasing the sampling factor k beyond this would not bring a significant gain. Wirh my set up of 3.95 I will investigate how to reduce this to a value of 3 to 3.5.
For information: the formule on page 81 of Planetary Astronomy should read F =206 Tp Di/Dp and not using factor 260.
