I own the iOptron GEM28 now for more than a half year. The first 3 months were horrible in terms of guided DEC performance, until I found the proper gear meshing and axis stiction by try-and-error. Now I’m satisfied with the guiding 🙂
Read more about my attempts here:
- Latest Update Part I Sept. 12, 2021
- Latest Update Part II Sept. 24, 2021
- Latest Update Part III Sept. 26, 2021
- Latest Update Part IV Oct. 2, 2021
- Latest Update Part V Oct. 12, 2021
- La(te)st Update Part VI Oct. 28, 2021
However, the annoying freezes of my GEM28 still occur. This is how such a freeze looks on a single exposure:
I notice a freeze when some of the direction LEDs of my MGEN light up constantly and the guide star starts to drift in one direction. From that moment on, my GEM28 stops to process guide signals.
The hand controller also usually no longer reacts to any commands. Sometimes even “back to zero position” doesn’t work anymore.
I replaced the MGEN cables, did a MGEN reset, upgraded the GEM28 and MGEN firmware, used different power sources… nothing seems to eliminate that unpredictable freezes.
I’ve to check every 2-3 shots if the mount is freezed again. If so, I can reset everything as follows:
- Stop guiding
- If possible back to zero position by hand controller or if that doesn’t work, manually to zero position… I already had both circumstances!
- Power off / power on
- Star alignment
- Back to my target and hopefully catch the same field of view like before the freeze
- Guider setup
- Start shooting again
This “reset” takes around 10-20 minutes and is super annoying! The problem only seems to occur when ST4 is used for guiding (according to many cloudynights postings)! There are people without such problems, but they all using ASCOM. Even with ST-4 some people reports no problems.
It’s a pity! I like the GEM28 for it’s weight and payload capacity (and also the look-and-feel). Without the freezes the GEM28 would be a fantastic portable mount!
Within total 25 sessions my GEM28 had 7 freezes (as of today, February 9, 2022). This is anything but reliable!
Update May 3, 2022:
No problems with my GEM28 the last 12 sessions. I’ve no explanation… Hope it stays that way!
ASCOM instead of ST-4
I contacted iOptron regarding the freeze problem and they suggested to use ASCOM instead of ST-4 for auto guiding, but this is a no-go for me, since I still don’t want to use a laptop for my astrophotography sessions. For this reason I ordered the AccuAlign version instead of iPolar at the time… and I still want using my DSLR, triggered by MGEN.
And now iOptron tells me indirectly to use a laptop… hmmm… No! The GEM28 comes with a ST4 guider port, so I want to be able to use it!
Hopefully iOptron will patch the ST-4 freeze problem with an updated firmware soon!
Don’t get me wrong: if you use ASCOM for guiding or even your GEM28 work constantly fine with ST-4 guiding, you’re a lucky guy.
I am not! And I know for sure, I’m not the only one with exactly the same freeze problem!
Star Adventurer GTi
Maybe a light on the horizon?
I’m very curious and looking forward to the lately announced SkyWatcher Star Adventurer GTi! It comes with all the features I would have liked to see on the original Star Adventurer.
Motors on both axes (RA/DEC) and GoTo, but (unfortunately) still
5 kg payload capacity.
Announced for May 2022!
So, iOptron has time to fix it before the GTi release… 😉