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Re: [ATM] Secondary Cage Calculations (formula from Kriege + Berry's book)
Dave,
Does that mean only certain eyepieces are useable with the scope? How
does the calculation affect illuminated area?
Am I to understand that if I want a broader f.o.v. for say, a ccd, I
should shrink the diameter to produce a larger cone? I assume this is
the case for astrographs.
- Jake
On 10/9/07, David Weinshenker <daze39@earthlink.net> wrote:
> Richard <cnc at cncservo.co.uk> wrote:
> Kriege + Berry are assuming a total angular field of view of 1/2 degree
> (i.e., +/- 1/4 degree from on-axis): thus they calculated the the extra
> diameter (for any aperture) required for this as:
>
> sin (1/2 deg.) times the focal length
>
> and then rounded sin (1/2 deg.) = .00873 up to .01 (1%)
> for convenience and to add a little extra margin.
>
> (Ref.: D. Kriege + R. Berry, "The Dobsonian Telescope", p.153-155)
>
> -dave w
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