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Old 22-07-2005, 08:31 AM
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Striker (Tony)
Whats visual Astronomy

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Join Date: Dec 2004
Location: Brisbane
Posts: 5,062
Not sure what Dob you got but being a 10" it will be more likely a 1250mm focal length at F5....the F number is just the ratio of the aperture to the focal length.....meaning your FL of 1250mm divided by the aperture 250mm = F5
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