Re: eye pieces
"Margo Schulter" wrote:
Thus with my 200mm/1200mm Sky-Watcher Dob, we have a focal ratio of f/6,
and a 7.5mm eyepiece should yield 160X. With a 203mm/1200mm scope,
another common specification, the focal length is the same, but at a
slightly faster f/5.91. With 203mm/1219mm, 8 inches at f/6, the focal
length is a tad longer, so that a 7.5mm eyepiece yields around 162.5X.
Again, these are rather minute distinctions.
The Meade Starfinder is designated as a 12.5" F5 but the mirror on mine was
marked on the backside in hand written permanent marker as FL 59.7", F4.77.
A 7.5mm Plossl may be longer or shorter, or have a wider or smaller field
stop than the design and numbers on the barrel suggest.
-Steve P.
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