If that subject line doesn't make sense -- that's okay. The business rebuilding Big Bertha reports that the refigure of the mirror by Swayze Optical was apparently quite successful:
A "Steve Swayze" refigured mirror for Clay's 17.5" F4.5 telescope. A first look with the optics shows beautiful "tight" pin-point stars.
No doubt this is a great mirror!!My guess is that DobSTUFF has seen a lot of telescope mirrors. This makes me more confident that the $810 I spent having Swayze Optical refigure and recoat the mirror was well-invested. I had never been completely happy with the optical performance of that mirror. Swayze's report was that it had a turned edge, which confirmed what I already suspected. I am hoping to improve on pictures like this:
and
Are you planning for astrophotography with the Dob mount? Everything I've read says you need a tracking mount, but I'm wondering if short-duration video cameras and stacking/alignment software will allow more photography with simple mounts.
ReplyDeleteShort exposures (1/8 second or less) don't require a tracking mount. There are platforms that provide up to about 20 minutes of tracking with a Dob, and that is on my list of things to buy.
ReplyDeleteDid they regrind the mirror, or just redo the coating?
ReplyDeleteA turned down edge can't be fixed by recoating. But if they had to regrind it (meaning to use the coarse abrasives) that would have been pretty expensive. I am pretty sure that they only repolished the surface (that uses a 5 or 3 micron cerium oxide), then did the semimagical reparabolizing process, which is what is called figuring the mirror. I call it semimagical, even though I have done this myself long ago on a 3" f/4.5 mirror.
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