Is Cheap Compatible With Not So Cheap?
Little bots mean a lot...

I have a problem with focusing my mind. I used to fidget in class, so I would bring in toys and hide them in my lift top desk. When lectures became boring, I would lift up the desk top and play robot wars, or dinosaur wars, or army man wars, or fighter jet wars… Hmm.. I do see the common denominator. In my defense, high school was a tough time for me, and for most of my teachers. So was college… all of them.

It just needed some space

The last installment’s virtual hand wringing occurred when I discovered I did not have the right combination of extender spacers to achieve a distance of 105mm back focus, as measured from the last optic on the telescope side to the face of the sensor on the camera side. Additionally, one reference point was improperly determined… by me. Yes, that does happen a lot.

For some reason, I decided to measure from the Celestron reducer’s shoulder, rather than the surface of the lens, a net 5mm error and I was without spacers to adjust. Astronomy, at least in the context of a telescope, requires a scrounge bag full of miscellaneous parts and accessories.

Purchasing from an exotic astronomy supply shop, Amazon, a M42x.75mm threaded set of 8 spacers was located for $21. Yes, these are considerably less than a similar set sold on an astronomy supply site. Am I worried about wandering spec, camera droop or vague threads? No. Computer control of manufacturing conserves use of resources through repetitive precision output, even to cheap parts.

In this case, spot checking part dimension and runout on a granite flat with a good dial indicator, they were all spot on. The M42x.75 threads are the camera’s native thread size, so no further thread adapters were needed beyond the initial 2″x24 to M42x.75 T Adapter.

Auto focus..

Focus is always critical and point of focus changes during dark skies long duration photo sessions. An automatic focuser, tracking to the camera’s image allows a telescope to be left unattended while collecting images over a long duration.

The automatic focuser is easy to install. It does require a unique ZWO mounting kit for the Celestron 8″ SCT. I purchased the Pro version for the same reasons as most people, it allows Bluetooth communication with the camera, it optionally adjusts to temperature feedback and there is the hope others may think I am not the astronomy newbie I am, but rather a pro.

So at this point the telescope if set up to take pictures, auto guide to maintain a centered target image, automatically adjust focus to keep pace with changes in the sky. Next up is software to bring it all together; telescope, mount, camera and automatic focuser. Should be interesting.

I misspoke in regard to the next step

The weight of the telescope and powered accessories was accumulating too much weight and exceeding 80% of the mount’s capacity without the use of a balance weight, 17.6 lbs. The capacity with a balance weight is 28.6 lbs, subsequently a ZWO Counterweight Balance Bar was purchased. The maximum weight that can be added is 11 lbs for the AM3N, so I was able to borrow an 11 lb weight from my Celestron mount that met that criteria  and was a good mechanical fit.

There is a tracking motion that could cause the telescope to come in contact with a tripod leg. I have not seen this travel, but that doesn’t mean it isn’t plausible. So I purchased a three strut ZWO 160 mm Pier Extension that raised the AM3N mount 6.3″ above the tripod and provided more clearance for movement. More important, it elevated the telescope and mount so I don’t have to crawl around in the dirt to get equipment set up.  The pier extension is load rated for 28.7 lbs, which is consistent with the balanced weight configured mount’s capacity. Now I am done, for now.

So I am onto evaluating and testing control software and getting devices to communicate with one another. Still not spring here in Maine. We had a little snow today, we’ll have a lot of snow tomorrow. Lots of brown mud prevailing.

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