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Can you help solve this mystery, please? Star Sense camera will not hold calibration with OTA after mount is rebooted.

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Can you help me solve this mystery, please?

I have a 2020 Celestron 8" Edge Evolution Ltd Edition 60 Anniversary model. The OTA is carbon fibre and some of the artwork is different but for in tents & purposes it's a standard 8" Edge Evolution

The Problem

The problem is, when the mount is switched off. the telescope will not maintain its calibration between Star Sense (SS) camera and the OTA. Please not I am not talking a SS alignment here - I'm talking about the calibration between the SS camera and OTA. 

This is what happens - I will do a SS Auto Alignment and the goto will be out by some margin IE. way outside of a 25mm eyepiece. So, I then calibrate the SS camera to the OTA, re-align, and everything is working perfectly. The goto is more or less in the middle of a 12mm eyepiece. Next time I reboot the mount, I do my SS Auto alignment and the goto is way off again  and I have re calibrate the SS camera to the OTA. Once I do that, everything works fine again. And so the cycle continues.  

Have you experienced this problem yourself or do you have an idea of what may be happening? Before you offer your suggestions, please read this list as what I have done to try and solve this issue:

1. The tripod and OTA are absolutely level before booting up the mount. 

2. Once I have booted up the mount, I enter time and my location, using GPS co-ordinates. I am extremely precise about this and am entering the correct time (and daylight saving as needed) to within 2 seconds. The GPS co-ordinates of my location as absolutely spot on as well - they are the same co-ordinates I use for all my telescopes and they are working perfectly. So this is defs not a time, date or location issue. 

3. The SS camera is mounted perfectly It does not move at all. I have the calibration problem even after rebooting without moving the telescope's position at all. 

4. I have even tried a new SS camera and handset. Exactly the same issue persists. 

5. The handcontroller, mount and camera have all the latest updates. 

6. The battery is working fine and holding it's charge perfectly.  

As I mentioned earlier, once the SS camera is re calibrated, everything works fine and the goto is accurate. The problem only arises after rebooting the mount. 

Any ideas, suggestions or sharing of similar experiences gladly welcomed, thank you. 


Edited by StarGazingSiouxsie
formatting corrected for colour
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Hi Siouxie.

Reading your point 3, I'm not sure this applies to you, but there's definitely a problem if the camera is removed and replaced each session.

Both the mounting bracket and camera bracket are tapered by 5mm, and the bracket has two triangular recesses into which the mounting bolts on the camera fit into. This leaves lots of "play", and depending on the order, and how you tighten the two bolts, there can be upto a degree of difference in the axes each time. I measured this by fastening a laser measure on the camera and marking the locations on a flat surface at the other side of the room then using a bit of trig.  It's hard to get the exact same alignment consistently each time you put the camera on. It's not just a lateral difference but vertical too, which I think comes from the bolts engaging with the recesses in the mount bracket.

I think the only practical options I can think of are to either do the added faff with the calibration each time, or leave the camera permanently mounted - which leaves it quite vulnerable.



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