DS series goto problem

spica42 · Post by **spica42** » Wed Sep 27, 2006 2:34 pm

I have a problem with my Autostar 2 stars align. After aligning north, I select the first star and the scope swings to around 5 degrees of the target. I'll use the controller to center the first star. After choosing the 2nd star, the scope swings to aroung 5-10 degrees of the 2nd target, I'll do the same with the controller.

However, after pressing enter, the msg displayed is always 'star allignment failed.' Anyone can help?

kingkong · Post by **kingkong** » Wed Sep 27, 2006 3:08 pm

which stars did you use?
5-10deg off sounds excessive, the mount is probably a bit far off north to start with...

Post by **VinSnr** » Wed Sep 27, 2006 3:21 pm

spica42 wrote:I have a problem with my Autostar 2 stars align. After aligning north, I select the first star and the scope swings to around 5 degrees of the target. I'll use the controller to center the first star. After choosing the 2nd star, the scope swings to aroung 5-10 degrees of the 2nd target, I'll do the same with the controller.

However, after pressing enter, the msg displayed is always 'star allignment failed.' Anyone can help?

which scope is this? The eq mount type (LXD55, 75) or the LX-90, ETX-125 type?

spica42 · Post by **spica42** » Wed Sep 27, 2006 5:53 pm

THe mount is the DS2000 series. It's suppose to hold a 5" Newtonion but I modified it to hold my Zenithstar ED II.

I use vega, altair or deneb.

jermng · Post by **jermng** » Wed Sep 27, 2006 5:58 pm

Make sure your OTA is aligned accurately to the mount. Cone Error can be a big headache - I've got the same problem with my SVP Push-To.

Also make sure the mount is totally level.

spica42 · Post by **spica42** » Wed Sep 27, 2006 6:21 pm

Cone error? What is that?

jermng · Post by **jermng** » Wed Sep 27, 2006 8:59 pm

basically your mount's axis is pointing at one point but because of the way you mount your OTA or some error in the mount itself, your OTA is pointing at a slightly different point.

Any experts on this? That's the extent that I know about this subject. The only way to get it right is to mount it properly or shim it where it needs ....

Post by **acc** » Wed Sep 27, 2006 9:52 pm

Cone error is only an issue with equatorial mounts. The DS series mounts are all alt-az, so the cause of the alignment failures is something else.

Spica, do remember to start a new thread when starting a new topic instead of posting in an unrelated thread. I have created a new one for you.

spica42 · Post by **spica42** » Wed Sep 27, 2006 10:27 pm

Thanks acc.

If I can fix this goto problem, I'll probably buy a good tripod and mount the mount onto the new tripod. This current one shakes like hell.

elton · Post by **elton** » Wed Sep 27, 2006 10:32 pm

The most common setup problems are :

1) your mount's alt axis is not perfectly perpendicular to the az axis. Check that there is little play in the alt bearings.

2) the view through the optics when swept through alt / dec cuts through a cone (hence cone error?) instead of a flat plane. Check that the way you mount your scope ensures that the optical axis is always perpendicular to the alt axis no matter how you turn the alt axis.

I suspect your problem is 2), which is similar to Jeremy's problem. This is most common when mating a scope to a mount not purpose built for it. It is one thing to mount the scope securely to the mount, it is another to ensure that it is absolutely orthogonal where it needs to be.

Liuming - food for thought for the new project?