The easiest way to look at the figure is to do an "eyeball Foucalt" test. If you are not familiar with this, you can look at the diffraction patterns on either side of focus. Thirdly, you can use a Ronchi eyepiece. I have always suspected the RV-6 I had was an "escape". (Escaped the figuring process.) I did not like the images that well. The 6"f10's I have put together always outdid the RV-6. Brent --- Richard Tenney <retenney@yahoo.com> wrote:
Brent,
I confess I don't know, only that it delivers what I consider a great image. What's the best/easiest method to determine the figure?
Rich
--- Brent Watson <brentjwatson@yahoo.com> wrote:
Rich,
I had a 6" Dynascope at one time. I found it in a pawn shop. The mirror was so dirty I was not sure there was a mirror in the scope at all! I tested the mirror and found it was a great sphere. Tha't OK if you want a sphere, but a parabola at f8 is quite different than a sphere - at least 1/2 wave. I have always wondered if it was just that scope, or were all Dynascopes spheres? How about yours? Chuck - is yours a sphere?
Brent
--- Richard Tenney <retenney@yahoo.com> wrote:
Got the following from a fellow on the Criterion Dynascope list today. Amazing webcam image obtained from this humble classic 6-inch newtonian (I'm still the original owner of a vintage 1972 RV-6, still my preferred grab-n-go scope)...
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This was captured with a Philips ToUcam Pro webcam through a Tele Vue 2x barlow with an extension tube:
http://www.unm.edu/~abqtom/images/Planets/Saturn/2004-03-22-TEW-Sat.jpg
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