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New SE mount aligned but tracking is horrible!!

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#1 astronet1

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Posted 17 February 2014 - 11:04 PM

I have a brand new SE mount. It was set up fairly level to the ground. It's only got a 5lb ED 72mm refractor and ln300 camera attached to it.

Alignment was on and set to sidereal. I did a SKYALIGN 3 start alignment and it said match confirmed, but when I set the camera to higher exposure (5+ seconds) my stars started becoming elongated.

What the heck am I doing wrong here?

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#2 astronet1

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Posted 17 February 2014 - 11:12 PM

:question:

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#3 Jeff2011

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Posted 17 February 2014 - 11:18 PM

Uh, that is an Alt Az mount. Not meant for long exposure AP. For that you need a GEM mount with autoguiding.

Edit: However with a good Alt Az mount you should be able to get up to 30 sec shots before field rotation kicks in.

#4 nodalpoint

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Posted 17 February 2014 - 11:23 PM

Hey Astro, check out the NexStar forum and there's a very long thread there of people doing some photography with the SE AltAz mount. You'll find a lot of suggestions there to help you get started.

#5 nodalpoint

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Posted 17 February 2014 - 11:30 PM

Here's the link to the thread:
Photography with NexStar Mount

#6 astronet1

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Posted 17 February 2014 - 11:37 PM

Hey thanks nodalpoint. Some interesting stuff there. Although it's making me even more frustrated my mounts not tracking looking at all those images!

#7 RTLR 12

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Posted 17 February 2014 - 11:59 PM

Have you turned the tracking on? I'm not sure that tracking is a default setting on a new SE mount. You may have to go to "Tracking" in the main menu and turn it on.

Stan

#8 astronet1

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Posted 18 February 2014 - 12:21 AM

Tracking was on and set to sidereal. I could hear it slowly moving so I know its attempting to track.

#9 gdd

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Posted 18 February 2014 - 12:49 AM

Does yours have the built-in wedge so you can track in equatorial mode?

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#10 astronet1

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Posted 18 February 2014 - 12:54 AM

No, but I'm only doing sub 30 second exposures for live video astronomy, so a wedge shouldn't matter.

#11 herrointment

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Posted 18 February 2014 - 01:03 AM

Try Auto Two Star alignment and use a higher power eyepiece. I believe that tracking is directly related to alignment accuracy.

#12 astronet1

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Posted 18 February 2014 - 01:18 AM

Three star skyalign is very picky. I have to get it just right or it fails. I'm limited in my area by trees, and two star points me to stars out of view, but I will try. To align I use cross hairs on the camera menu. The objects get perfectly centered.

Edit: I will try again tomorrow night aligning but maybe I do need a cross hair eyepiece?

#13 T1R2

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Posted 18 February 2014 - 01:39 AM

also make sure your alignment stars that you choose are spread far apart as possible and close the celestial equator, this is where knowing the names and location of not so well known stars and some well known stars, this is where a star atlas is very important, you probably already know that though

#14 Jeff2011

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Posted 18 February 2014 - 01:44 AM

I have not tried imaging on my Nexstar, but I used it the other night at an outreach event and aligned on Jupiter with a reticle eyepiece and it tracked well and the goto was pretty accurate. I would think if you did a 3 star with a reticle eyepiece you should be able to get 30 second shots with your setup.

#15 mclewis1

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Posted 18 February 2014 - 09:04 AM

Good balance, backlash compensation, and an accurate initial alignment ... carefully follow the guidelines on how to do this posted in the NexStar forum. Then you'll likely find your SE mount tracking substantially more accurately. It's not going to be like an EQ mount and most folks know this but with a little effort and some practice they can do a very respectable job.

#16 RAKing

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Posted 18 February 2014 - 06:20 PM

You might not be doing anything wrong, but let's take a step back to the basics.

What power supply are you using? These mounts are touchy about input voltage. I always ran mine with a solid 15 volts and never had any issues with tracking.

Is it making good connections to the 2.1mm pin jack? (You can spread the leaves of the pin with an Exacto knife and a #11 blade - be careful - but it's highly recommended.)

For visual, you can get away with a glitch now and then from your power supply. It isn't enough to reset the mount, but it does miss a beat here and there. For AP, you don't want that. Fill the battery holder with fresh batteries. They do not run the mount; they are your back up supply.

The Celestron tech guys told me that 90 percent of user's problems can be traced to their power supply or connections.

I'm just covering the obvious. :)

Cheers,

Ron

#17 RAKing

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Posted 18 February 2014 - 06:34 PM

It's been a while since I used my SE and I'm still remembering things!

1. Tape your power cord down or tie it off. Make sure it is not dragging or catching on anything. You don't want any pressure on that pin jack.

Have you broken your mount in? Turn Cord Wrap "Off", then run the mount around the azimuth axis a couple times in each direction. IIRC, it take a minute to go around and this will spread the "Glue grease" Synta uses and help get the gears meshed. You can also do the same thing with the altitude axis. (Take the scope off first! :lol:) We can adjust the altitude axis fairly easily, so I never had any problems with it, but you have to depend on electricity to move the azimuth axis, so it pays to be sure it's as smooth as possible.

Hope this helps,

Ron

#18 astronet1

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Posted 19 February 2014 - 12:32 AM

Thanks everyone. I will try to break in the mount tomorrow. I was using a 5000MAH battery for the mount and camera. Should have been enough but I will try again using a car battery tomorrow night.

As far as the mount being caught up on a cable, I have everything zip tied with enough play for 360 AZM and 180 ALT, so that shouldn't be a problem.

#19 RAKing

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Posted 19 February 2014 - 07:16 AM

Thanks everyone. I will try to break in the mount tomorrow. I was using a 5000MAH battery for the mount and camera. Should have been enough but I will try again using a car battery tomorrow night.

As far as the mount being caught up on a cable, I have everything zip tied with enough play for 360 AZM and 180 ALT, so that shouldn't be a problem.


That all sounds good and 5000mah should be plenty. I use 5000mah li-pos to run all my gear, too.

You might also check the balance of your refractor/camera and the backlash settings on your mount. There is always slop in the gears and you want them to be positively engaged during a photo run. Some of us deliberately shift the balance to be "East Heavy" by a few ounces. This keeps the gears engaged better on our GEMs and might also help your alt-az mount..

Finally, the SE mount is a great little mount, but the tripod is a bit 'wimpy'. A little breeze is all it takes with one of those.

Best of luck. Astro imaging can be a very frustrating hobby and you just have to keep trying. :)

Ron






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