Re: [ATM] very long focus objective

["Bob May" <bobmay@nethere.com>]

Probably the biggest silly factor with Richard's triplet is that it is a
triplet!
A doublet with ordinary glasses will probably provide a diffraction limited
image without hardly any work.
The 200" refractor that I have has a very broad area where an image is
formed and something 6 times longer will really have a large volume where a
EP may be placed and have a good image.  I do my focusing by looking at the
size of the blue and red blurs and sort of equalize their size.  This tends
to put the brightest focus point of my eye in the focus area of the
objective.
Bob May
http://nav.to/bobmay
bobmay@nethere.com
NEW! http://bobmay.astronomy.net


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