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Old 16-01-2008, 11:44 PM
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EzyStyles (Eric)
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Imaging with different focal ratios

Hi guys,

I have this stupid question which is bothering me. Would imaging lets say a 10" F/5 reflector + 2 x barlow making it F/10 will be the same as a 10" F/10 cassagrain?
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Old 17-01-2008, 12:16 AM
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madtuna (Steve)
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The only stupid question is the one you don't ask.
Watching this thread with interest as I've been wondering the same thing
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Old 17-01-2008, 08:38 AM
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Should be the same speed/field of view as the f/10 Eric...
But I have always wondered will you get less coma like a f/10 primary or are you still stuck with the level of a f/5?
I have always wondered this?
cheers
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Old 17-01-2008, 08:48 AM
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sheeny (Al)
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I would think so... ignoring minor effects like the larger secondary obstruction in the SCT, extra light loss in the barlow, etc.

Al.
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