After almost 2 weeks with the iOptron GEM28 I want to share my first impressions, even if I still were not able to test the mount in the field due to bad weather… So far, I found 2 issues:
- Saddle Locking Knob scratches on the DEC unit
- Polaris seems to be on a wrong position on the hand controller
Saddle Locking Knob scratches on the DEC unit
In a certain position, the dovetail saddle locking knob scratches on the DEC unit!
Scratching 
No scratching
So I contacted the iOptron support. They told me to remove the saddle and check if there is any debris between the axis and the saddle. Additional I should rotate the saddle 180° when I put it back. All done, but still scratching on the DEC unit…
Their last suggestion was successful: Put a nylon washer between the knob and the saddle. Now the tightened knob position is perfect. No scratching anymore 🙂
Polaris is on the wrong position
As already mentioned, Polaris is on the wrong position on the iOptron hand controller compared to other polar finder apps. The reason is simple: it takes into account refraction correction. Read more here.
StarAdventurer Mini App: 03h23m 
Polar Finder App: 03h24m 
iOptrom GEM28: 3h15m
Besides the saddle knob problem (which is anyway already solved with the nylon washer), I’m very happy with the GEM28. Maybe I’ll be able to test it next week in the field, if the weather forecast is correct 😉
