TheSkySearchers

Hello everyone, i have an iOptron CEM40EC bought second hand and i cannot get round stars... seems as the mount is always moving one way or another... Anyone with this mount has this issue or know how i can resolve it? Great mount but...

Hopefully some of the iOptron users will be along soon to help figure this out.
Welcome to the forums as well

Makes you wonder why the original owner sold such a new mount so quickly..How was the seeing at the time? What telescope /camera combo were you using? I have the cem120 non EC, owned for around three years, I find it pretty great but seeing conditions play such an important part of getting good results.

Hello !
I'm not a specialist for CEM40EC, but I wonder where is the North on the picture, maybe this could help the diagnosis of the shape.
Arsène

I had some similar issues with an earlier CEM40EC and contacted iOptron and sent that one back and they recently shipped me the very latest version, which has the newer 28mm shaft and the 8"dual saddle. The smaller USCS (saddle) and smaller diameter shaft is the older version. The most current version has counter weight that is the 8027. In regards to your oblong stars, the CEM40/CEM40EC must be accurately leveled and properly balanced in both RA and DEC. If not, improper load distribution could possibly cause what you are seeing as worm gears/motor belt tension may be chattering a bit if not properly balanced - or just needs to be adjusted. Take a look at this guide: (http://www.ioptron.us/Support/CEM40_Bel ... on_Adj.pdf). Also, if you are not using an AutoGuider, your exposures are going to be a lot shorter. Take a series of 5 second exposures in two different locations of the sky (East and West) and see how the oblong stars compare. iOptron Tech guys are really good, so if you haven't already reached out to them, I suggest they could help you out. It could take a few days for a response, but I've had great luck with them. To me it seems that you may have an inaccurate leveling and balance issue, tension issue, or both. Leveling the mount and balancing REALLY need to be very good for all to work well. I can get up to about 5 minute unguided exposures, but usually don't need exposures to be that long on most objects, so I don't auto guide too often. You may also try calling them, starting a few minutes before their operation hours - which I've done and actually have been able to catch someone before their day goes nuts. Good luck, the CEM40EC is a great mount.

Hello Starcruz.

Could you post up some details of the image, exposure duration, guided/unguided, what part of the sky etc. And can you describe how you polar aligned the mount.

Welcome to the forum.

Regards

Graeme