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Re: [ATM] Diagonal size
1.83 inches (46.5 mm) is a common diagonal size for an 8in f/6 scope and
most folks don't mind the 23% obstruction. If you want to use a smaller
secondary (e.g. 1.52 inch or 38.6 mm), get a low-profile focuser and the
field should be acceptable to the edge for visual observation.
Orion Telescopes sells a 1.57in (40mm) secondary for $21 plus shipping.
JMI sells some low-profile focusers for $79 to $129 (less if you buy a
"kit").
Jeff Anderson-Lee
Adeildo Sombra wrote:
>Hello All.
>
>I 'm finish a 8in. f/6 mirror and trying to figure out the proper size of the diagonal.
>I have a focuser 80 mm tall and intend to have a tube of 240mm diameter. I did the
>calculations and found that the m.a. of the diagonal should be 42mm, but this is higher than
>20% of the primary mirror. I read that the obstruction rate should be beetwen 16 and 20%.
>This telescope will be used only to direct observation, no cameras or whatever...
>
>Does anyone have a suggestion?
>Thanks in advance.
>Adeildo.
>
>
>
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