Hi Feroze, Remember, the sun and moon both move about 0.25 degrees per minute through the sky. Here are some representative long lens angle of view numbers:
4.1 deg SMCP-A* 600mm f/5.6 ED (IF) 4.1 deg SMCP-FA* 600 f/4.0 ED (IF) 2.1 deg SMCP-A* 1200mm f/8.0 ED (IF) So, let's postulate that at 2000mm you're looking at an angle of view of around aov = 2.1 * (1200/2000) = 1.26 So in five minutes either one will completely cross the frame on the diagonal. In reality, you want to keep it closer to the center of the frame, so you're looking at adjusting your "aim" every minute or two. TTYL, DougF KG4LMZ
