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Old 08-09-2020, 05:29 PM
Placidus (Mike and Trish)
Narrowing the band

Placidus is offline
Join Date: Mar 2011
Location: Euchareena, NSW
Posts: 3,545

Could you explain what the different thumbnails are? Are they "before and after fixing the focusing issue", or are they "early, middle, and late night" to show there's no shift, or are they different processing, or as Ellery Queen said, "someone else entirely"?

Perhaps you could give the different thumbs explanatory names, or perhaps you could put captions on them.

I'm assuming that the idea of the near-infrared filtered image for luminance is to take advantage of improved seeing in the near infrared. If so, perhaps you could edit your post accordingly.

Regardless, any single one of them looks magnificent. Well done!

We have a 20 inch PlaneWave, with their three inch throat focuser, carrying about 20 kgs of FLI PL16803 camera, 8 position 50 mm square filter wheel, off axis guider, guide camera, and lots of power and data cables. As supplied, that flops about all over the place, with gross camera tilt as the scope tracks in RA, and resultant marked change in focus. We added a radially placed spring-loaded strut (think of a car's front suspension) so that the focuser can still move in and out +/- a couple millimeters, but is constrained in the RA direction to stay exactly on-axis. That was chalk and cheese. The key point is that the focuser wasn't moving in and out, it was flopping sideways. (The attached photo shows an earlier version with an Aspen camera. The new camera is heavier and the strut system much stronger again).
Attached Thumbnails
Click for full-size image (010 strut.JPG)
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Last edited by Placidus; 08-09-2020 at 05:52 PM.
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