|
Quoting the focal ratio in their images is a bit misleading, it just tells you how much light is let in. The focal length determines the magnification.
SCT's (like the 10" LX200) are good for planetary imaging because their native focal length is 2500mm, where my 10" native focal length is 1250mm, half the length. For me to get the same image scale, I need a 2x barlow.
For deep space imaging, the faster scopes are letting in more light, and don't need exposure times as long. Anyway my DSO imaging understanding is limited.
But for planetary and lunar, it's more important to quote the focal length, because that's what determines the magnification, the image scale.
|