From: "Mel Bartels" 
To: 
Reply-To: "Mel Bartels" 


>>>
I am asking the list to advise me on a couple of issues. Firstly, I need to know what
would happen if the grinding operation was shortened so dramatically as to make a
40 m focal length for a 1 meter diameter mirror. Would this imply a poor figure?
Secondly, I am interested in any gain in acuity. What there be a meaningful increase
in the angular resolution using scopes with such long focal lengths?
<<<

The quality of the figure is measured in wavelengths of light.  The sagitta
or depth of the mirror has nothing to do with this. Except that you will
find a f/40 1 meter scope as difficult to figure as any 1 meter scope
though the shallowness of the parabolization will make it somewhat easier.

There is no meaningful increase in resolution by varying the focal ratio.
The resolution, assuming acceptable objects, is set by the aperture.

Your biggest problem by far will be the testing tunnel that you will have
to construct to test the optic and the tunnel that you will need when using
the mirror.

Mel Bartels

--- BBBS/NT v4.00 MP