Quote:
Originally Posted by richard2600
Hi can someone tell me whats the difference if you have 2 telescopes both 5 inch in diameter one has fl of 650 and the other fl 1250. Dose this mean the one with bigger focal lenth has more power or better focus
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The first one is F/5 so it gathers light faster. You'll get a brighter picture. The second one is nearly F/10. Your view will be magnified but very dark. Cropped compared to the F/5 FOV. It's likely the F/10 view will look blurrier as well.