Thread: F-ratio myth
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Old 20-02-2018, 11:36 PM
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Peter Ward
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Join Date: Dec 2007
Location: The Shire
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Quote:
Originally Posted by AstroJunk View Post
Fortunately for me I have two telescopes that I can compare directly. One is a 14" SCT using Hyperstar and has a focal length of 711mm. The second is a 4" Refractor with a focal length of 714mm so they are both effectively the same.

I happen to know that one of the scopes requires much less of an exposure to get a high signal shot of a 14th mag asteroid than the other using the same camera. That's simple physics, photons per pixel. I even had a paper published in the Journal for Occultation Astronomy on the subject
Sooo... a C14 gathers more light than a 4" ?

I'd really like to hear from any Ceravolo dual FL owners on whether they see better S/N in the "fast" configuration.
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