AZ Mount not tracking properly

[montezuma110]

My mount is a Skywatcher AZ Goto mount. Telescope is 1500mm 5inch Mak-Cassegrain.

As i began capturing images last night i noticed that it was not following the stars correctly and i was getting star trails, even on a 20sec exposure. I Tried re aligning it but still got star trails. After looking back over my images the trails do not look like field rotation. I have imaged with this mount before at 30 sec subs and had no issue.

As far as i am aware i carried out the normal alignment process as per usual.

The only thing i have noticed recently is that when slewing the horizontal axis is sometimes sluggish and varies its speed.

If anyone has any suggestions what the problem may be then they would be greatly appreciated.

Thanks

I have attached two images comparing tracking from last night to September 2012. They are both 30 second exposure, through a 1500mm scope.

Jan 2013

Sept 2012

[Ewan]

I'm not too familiar with your setup but it looks like a 5" Mak could be pushing that mount to it's limit, i have seen some internet quotes stating 4.5kgs is about max, you may want to have a tally of your payload.

[montezuma110]

Just checked, the load was 4.7kg, sounds like it could have been the weight.

Now I think about it when I took the picture last year the camera was mounted on the diagonal mirror, as supposed to mounted in a straight line. Guessing having the weight of the camera further out from the pivot point wouldn't have helped.

Guessing there is nothing else I can do apart from buy a new mount.

Thanks

[mallorcasaint]

As it's an AZ mount then it won't track sufficiently for good astro photography as you will get rotation. You need an EQ mount to track the sky properly.

[dph1nm]

Rounds stars in 30s at 1500mm focal length is pushing it even for a top end EQ mount, never mind one of these cheap AZ ones! I have the Celestron equivalent (Nexstar SLT) and even at 660mm FL I struggle to get 30s shots.

NigelM