Go Back   IceInSpace > Beginners Start Here > Beginners Talk

Reply
 
Thread Tools Rate Thread
  #1  
Old 03-02-2019, 09:02 AM
Pepper (Steve)
Registered User

Pepper is offline
 
Join Date: Dec 2018
Location: Tamworth
Posts: 49
Synscan mount tracking wierd

Help please people!
So up until the other night when i set my gear up and do an alignment I was able to leave the scope for a while without the star drifting off too much.
Last night I was out after a long cloudy period to get busy testing the new computer. Much to my dismay, the stars seem to drift waaaay to fast?
With sidereal tracking chugging away the star will drift (movement every second) from centre towards the rhs of finder. I need to up and right button to recenter.
Turn tracking off and they rapidly start heading toward bottom left of finder.
Now this was never anywhere near as pronounced on any previous night.
Canít even get a 2 second shot now??
Any ideas? This is driving me mad.
Reply With Quote
  #2  
Old 03-02-2019, 09:38 AM
brian nordstrom's Avatar
brian nordstrom (As avatar)
Registered User

brian nordstrom is offline
 
Join Date: Apr 2007
Location: Perth WA
Posts: 4,316
Steve , it sounds like your mount is running in reverse eg. it's set for the northern hemisphere ,,,, not the southern .

Brian.
Reply With Quote
  #3  
Old 03-02-2019, 09:41 AM
JA
.....

JA is offline
 
Join Date: Oct 2016
Location: Melbourne, Australia
Posts: 1,308
You could go through the (myriad of) settings and look for inconsistencies and/or try a reset.

Bets
JA
Reply With Quote
  #4  
Old 03-02-2019, 09:54 AM
Pepper (Steve)
Registered User

Pepper is offline
 
Join Date: Dec 2018
Location: Tamworth
Posts: 49
Done factory settings in handset and settings all remain the same.
Got me buggered, sat up till 330am this morning and nothing makes any difference.
Reply With Quote
  #5  
Old 03-02-2019, 10:37 AM
Pepper (Steve)
Registered User

Pepper is offline
 
Join Date: Dec 2018
Location: Tamworth
Posts: 49
Quote:
Originally Posted by brian nordstrom View Post
Steve , it sounds like your mount is running in reverse eg. it's set for the northern hemisphere ,,,, not the southern .

Brian.
Thatís interesting Brian. What would cause that?
Iím pretty sure I set the location to south?
Reply With Quote
  #6  
Old 04-02-2019, 10:28 AM
brian nordstrom's Avatar
brian nordstrom (As avatar)
Registered User

brian nordstrom is offline
 
Join Date: Apr 2007
Location: Perth WA
Posts: 4,316
. Check you have entered a - degree setting , Also try taking your OTA ( Tube ) off and turning it 180 degrees then turning the mount and tube
so they are are pointing up again . , this will turn the RA of the mount 180 degrees , hope this makes sense .

I know this could be a silly question , but the mount is pointing south ? not north , sillier things have been done by us all .

Brian.
Quote:
Originally Posted by Pepper View Post
That’s interesting Brian. What would cause that?
I’m pretty sure I set the location to south?
Reply With Quote
  #7  
Old 04-02-2019, 03:07 PM
Pepper (Steve)
Registered User

Pepper is offline
 
Join Date: Dec 2018
Location: Tamworth
Posts: 49
Yeah def pointing south...........ish
Did a little testing yestiddy while cooking tea, I let it run and monitored the axis movements. Dec didn’t budge, ra was tracking at 1 degree/4 min and seemed to be rotating the correct way.
I did notice however my altitude setting screws were a few deg out. So polar alignment was probably bad.
Would my symptoms describe bad polar alignment?
Reply With Quote
  #8  
Old 04-02-2019, 04:49 PM
JA
.....

JA is offline
 
Join Date: Oct 2016
Location: Melbourne, Australia
Posts: 1,308
Quote:
Originally Posted by Pepper View Post
Yeah def pointing south...........ish
Did a little testing yestiddy while cooking tea, I let it run and monitored the axis movements. Dec didn’t budge, ra was tracking at 1 degree/4 min and seemed to be rotating the correct way.
I did notice however my altitude setting screws were a few deg out. So polar alignment was probably bad.
Would my symptoms describe bad polar alignment?
Yes, especially as you say you ...

Quote:
Originally Posted by Pepper View Post
need to up and right button to recenter.
That's not to say that there may not be other issues, but certainly a large error in polar alignment would have similar symptoms to what you reported. As to the apparent speed of the motion across your display, that would depend on your focal length and the angular distance the object is away from the South Celestial Pole.

To understand the abberant motion you mentioned think of two circles that need to be concentric around the South Celestial Pole: one describing the true star motion and the other the rotational axis of your mount. Now set these two circle centres askew vertically to try to recreate your altitude error and you can possibly see how this could lead to the abberant motion you observed. I think it's a good thought experiment.

Best
JA

Last edited by JA; 04-02-2019 at 05:01 PM.
Reply With Quote
  #9  
Old 04-02-2019, 05:59 PM
Pepper (Steve)
Registered User

Pepper is offline
 
Join Date: Dec 2018
Location: Tamworth
Posts: 49
Thanks mate, I only just read a good website that explained what you did above.
I’ll give it another go tonight and see how things pan out.
Reply With Quote
  #10  
Old 05-02-2019, 07:57 AM
Startrek (Martin)
Registered User

Startrek is offline
 
Join Date: Dec 2017
Location: Sydney
Posts: 940
Make sure you enter the correct time into the handcontroller
Remember itís US. Month / Day / year
A few degrees out in PA is going to make your stars drift quickly depending on your altitude and azimuth
I attached an old school way but good way to align your tripod and mount toward true celestial south called the solar noon meridian method better than a compass with magnetic declination setting
Also attached the Synscan Polar alignment routine which works for me every time , gets to sub arc minute alignment
Make sure you balance your mount in both axis and set your home position correctly
Good luck
Cheers
Attached Thumbnails
Click for full-size image (8E325C09-5B6F-4AD5-862D-17C92E421B2D.jpg)
161.1 KB17 views
Click for full-size image (0B9C5B13-ED05-450C-82BE-7A662571407F.jpg)
124.2 KB9 views
Click for full-size image (18AA63F9-B5A6-4ADF-996E-9DEBF104F7FD.jpg)
131.0 KB11 views
Click for full-size image (B28F33C9-62CF-4463-B2B0-394B63053A5D.jpg)
137.5 KB10 views
Click for full-size image (36D21385-1EEF-4E1D-8E42-EAA0CBD494DA.jpg)
137.0 KB11 views
Click for full-size image (FCFA5653-4F67-4A6B-A862-E1F78FFD8352.jpg)
124.5 KB11 views
Reply With Quote
  #11  
Old 05-02-2019, 08:14 AM
Startrek (Martin)
Registered User

Startrek is offline
 
Join Date: Dec 2017
Location: Sydney
Posts: 940
Missed one important item, make sure your tripod is perfectly level , forget the in built bubble level on the mount head use a good Stanley boat level 300mm long not a cheap plastic one and level across 3 axis on top of the tripod base with the mount removed, then install your mount head
Cheers
NB: the tripod must be on a solid surface like pavers, concrete, stone, rock etc... not grass or gravel / soil
Reply With Quote
  #12  
Old 11-02-2019, 01:50 PM
tvandoore (Tim)
Registered User

tvandoore is offline
 
Join Date: May 2016
Location: Buderim
Posts: 35
I've had this type of thing before (possessed goto behaviour) caused by embarrassing errors like getting the E/W, N/S in the GPS coordinates wrong, using deg/minutes coordinates instead of decimal (and vice versa), having tracking switched off/the track rate incorrect, the RA/DEC motor drive cables plugged in around the wrong way (older GOTO design than the eq5) etc etc.

I think the synscan the N/S in the GPS coordinates is entered as +/-, we are minus in Australia.

Suggestion - when you point it roughly at the SCP, does a goto command (say rigel Kent) get remotely near the target? If it goes off somewhere random, it's likely a gps location issue. If it goes to where it was/will be (somewhere in the arc around the SCP), more likely be a time/date issue. If it gets it pretty close, but won't track, I'd look at the tracking rates/basic setup.
Reply With Quote
  #13  
Old 12-02-2019, 12:41 PM
Wavytone (Nick)
BigBanger

Wavytone is online now
 
Join Date: Jul 2008
Location: Killara, Sydney
Posts: 3,700
Here's the Idiots Guide aka "SYNSCAN for beginners":

1. Forgetting to level the tripod (D'uh).
2. Forgetting to set the mount with the RA axis aimed roughly at the pole (using a compass).
3. Forgetting to align the mount to +/- 0.5 degree with the pole (using dec circle or drift method).
4. Forgetting to put the scope in the PARK position before power-up the handset (and you wonder why it slews 90 degrees off, or into the ground...)
5. Forgetting to clamp the axes before commencing the SYNSCAN alignment routine.
6. "Fat finger" or ID=10T errors when configuring the SYNSCAN handset - eg setting the latitude to N when it should be S, timezone to being - 10h instead of +10h, daylight saving on/off.

All of the above play havoc. Only solution is to redo all the steps.

Symptoms:

A. If all works more-or-less but GOTO are consistently off by a degree or so in some direction, redo steps 1, 2, 3, and check the clutches are firm. If the clutches are locked and you're sure the rest was OK, use the PAE function to force a correction in particular areas of the sky, or redo from scratch.

B. if the result is an objects consistently drift in dec, and GOTOs are off be a few degrees, you missed steps 2 or 3.

B. During the SYNSCAN alignment, if the first slew to a target is way off target (ie >10 degrees, possibly 90 degrees or more) you have probably missed steps 4 or 5 or you have committed sin #6.. = power off and redo from scratch.

C. Failing to clamp the axes is fatal. This results in wacky results - some GOTO's will be close, some will be waaaay off. Power off and redo from scratch.

D. Slipping RA clutch - when clamped, push the scope in RA and it slips. As alluded to recently, if you are using an AZEQ6 the RA clutch can slip - no matter how tight the handle is pushed - when the clutch material has compressed with use. A temporary fix is to balance your scope so it doesn't slip when clamped. But a more permanent fix may require maintenance - ie disassembly - to fix the clutch.

Last edited by Wavytone; 12-02-2019 at 01:08 PM.
Reply With Quote
  #14  
Old 12-02-2019, 01:58 PM
Redeye
Registered User

Redeye is offline
 
Join Date: Jun 2018
Location: Canberra
Posts: 11
I think this is good advice regardless of the mount. I am having goto issues with my CGX which I hope to rectify using these tips and others in the post I raised.
Reply With Quote
  #15  
Old 14-02-2019, 07:36 AM
Pepper (Steve)
Registered User

Pepper is offline
 
Join Date: Dec 2018
Location: Tamworth
Posts: 49
Hopefully clear nights over the weekend to get this in order.
Thanks for suggestions guys. I’ll keep yas posted
Reply With Quote
Reply

Bookmarks

Thread Tools
Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +10. The time is now 11:33 PM.

Powered by vBulletin Version 3.8.7 | Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.
Advertisement
Meade Australia
Advertisement
Bintel
Advertisement
NexDome Observatories
Advertisement
Nitecore
Advertisement
Lunatico Astronomical
Advertisement
SkyWatcher Australia
Advertisement
OzScopes Authorised Dealer
Advertisement
Astronomy and Electronics Centre
Advertisement