It was also cloudy; this was snapped between the clouds, and actually with a little haze still present. Kenko Sky Memo S equatorial mount and clock drive, with alignment only guessed at using a compass, and yet the tracking worked reasonably well -- about as well as I ever used to manage with my old Edmund Scientific reflector, but not nearly as good as I managed last week using the polar scope.
If I'm doing the math right, a 90mm objective observing 600nm (orange) light has a diffraction limit of 8 microradians, or 1.65 arc-seconds. The moon here is about 2700 pixels across, smallest features are 5 pixels or less, call it 1/500th of the moon's diameter. 1/500th of 1800 arc-seconds is about 3.6 arc-seconds, so I might actually be close to the maximum theoretical resolution? Off by less than a factor of two would be pretty good. At first glance, I didn't think this scope was anywhere near that good. There does seem to be some scattering I can see in some of my test images, which definitely adds noise/reduces contrast.
Definitely still a lot of learning to do to get the best out of this new tool, but not a bad first effort.
Seeing at sea level is usually not that great, probably never better than an arcsecond. So That's not bad. I will see if I can save the image and zoom in -- the blog app did not allow a zoom. Try an open cluster or some star cluster so you can really test the seeing and optics.
ReplyDeleteJust to follow up, indeed one can zoom in once you save the figure. Interesting how most craters look like they are nearly perpendicular to the surface -- in other words not too many oblique impact angles. Curious.
ReplyDeleteThanks!
ReplyDeleteI think I got one tonight that's *slightly* better of the Moon.
(For some reason, Blogger doesn't notify me when there are comments...)