Go Back   IceInSpace > Images > Deep Space
Register FAQ Calendar Today's Posts Search

Reply
 
Thread Tools Rate Thread
  #1  
Old 17-07-2006, 02:19 PM
EzyStyles's Avatar
EzyStyles (Eric)
I HATE COMA!

EzyStyles is offline
 
Join Date: Jan 2006
Location: Melbourne, Victoria
Posts: 3,208
Test on autoguiding (Keyhole)

Hi Guys,

Had a chance to test the autoguiding port on the EQ6 last Thursday night with the DSI II. This is done from the GPUSB unit from http://www.store.shoestringastronomy.com/index.htm

Software used for autoguiding on the EQ6:
- Guidestar v1.1
- Virtual Serial Port
- Envisage

Guidescope:
- 4 inch newt
- DSI

Imaging Scope:
- 8 inch GSO newt
- DSI II

Processing:
- Registax for stacking
- Photoshop CS2
- Astro Tools

Dark frames were not taken as purely i wanted to test the autoguiding. Focus was off and bright moon so i wasnt about to post it stars are abit oval not sure if this maybe caused from the rough polar alignment.

Consist of 6 x 2minute 49 second .

Comments welcome.
Attached Thumbnails
Click for full-size image (1.JPG)
88.4 KB56 views

Last edited by EzyStyles; 17-07-2006 at 02:56 PM.
Reply With Quote
  #2  
Old 17-07-2006, 03:55 PM
EzyStyles's Avatar
EzyStyles (Eric)
I HATE COMA!

EzyStyles is offline
 
Join Date: Jan 2006
Location: Melbourne, Victoria
Posts: 3,208
here's one of m8 on the same night with my regular exposure time of 84 sec. 15 x images stacked. I have darks for 84 sec

still the stars seem to be funny shaped again?
Attached Thumbnails
Click for full-size image (m8_15x84_AG_final.JPG)
56.5 KB37 views
Reply With Quote
  #3  
Old 17-07-2006, 04:07 PM
Striker's Avatar
Striker (Tony)
Whats visual Astronomy

Striker is offline
 
Join Date: Dec 2004
Location: Brisbane
Posts: 5,062
HI Eric,

Autoguiding is not as easy as it sounds......as you can see everything has to be working spot on if you want to autoguide for any length of time.
Thats the complexity of getting good images...the more you can improve the tracking quality of your mount the more impresive your images will become.

To get nice round stars for exposures over 60 second is what you will strive to master over the coming months.

What settings did you use for guiding...there is lots of members that can help you in this department.

Have you done any PEC training.
Reply With Quote
  #4  
Old 17-07-2006, 04:15 PM
EzyStyles's Avatar
EzyStyles (Eric)
I HATE COMA!

EzyStyles is offline
 
Join Date: Jan 2006
Location: Melbourne, Victoria
Posts: 3,208
cheers Tony. It seems my stars are more rounded without autoguiding. Ive set autoguiding speed to .25 , backlash at 5500 for RA and DEC (not sure if this is correct) how would i find out what backlash should be set to?

working on PEC atm
Reply With Quote
  #5  
Old 17-07-2006, 04:24 PM
Striker's Avatar
Striker (Tony)
Whats visual Astronomy

Striker is offline
 
Join Date: Dec 2004
Location: Brisbane
Posts: 5,062
Dont be concerned Eric....your not that far off.

Regarding backlash just leave it default at the moment...your the only one to see backlash...I have some backlash in my mount but if it's not to bad it's not a problem at all...play with the settings.

How about all the settings under guidescope...????
Whats your guide star doing...do you see it slowly return to it's centered position or does it go to far...you want the eroor corrections to be very small.
Reply With Quote
  #6  
Old 17-07-2006, 04:32 PM
EzyStyles's Avatar
EzyStyles (Eric)
I HATE COMA!

EzyStyles is offline
 
Join Date: Jan 2006
Location: Melbourne, Victoria
Posts: 3,208
thx Tony. Using Envisage to autoguide. The guidestar appears to stay dead centred though? it is very weird but these elongated stars happen before autoguiding also . I was hoping autoguiding will get rid of it but....

refer to post:

http://www.iceinspace.com.au/forum/s...ad.php?t=10957

i wouldn't say this time the stars are doubling up though but they are funny patterns esp from the M8 shot.
Reply With Quote
  #7  
Old 17-07-2006, 07:54 PM
avandonk's Avatar
avandonk
avandonk

avandonk is offline
 
Join Date: Aug 2005
Location: Melbourne
Posts: 4,786
You are at a very high mag. First establish which direction the stars are elongated. My bet is in declination. Overcorrection can lead to this problem.

Bert
Reply With Quote
  #8  
Old 17-07-2006, 09:32 PM
Doug
Registered User

Doug is offline
 
Join Date: Mar 2006
Posts: 645
G'day Eric, I tend to agree with Bert. You seem to have dec drift and this is most likely caused by incorrect dec backlash compensation, and also perhaps, too long a time interval between guide corrections.
The other image unguided that you linked to is the result of out of balance OTA I believe. And that might be part of your current problem as well. It would be interesting to know what your guide exposure time is? Not sure what you mean by 'guide speed=.25. Is that aggressiveness or guide exposure time? Not sure what you mean by RA backlash. Guide corrections for RA typically either speed up the drive, slow it down or maybe even stop it briefly. It is not usual to actually reverse direction of RA, so backlash would not be an issue. Depending on the brightness of your guide star, you might find guide exosures of 2 to 8 seconds should work well for you. From Memory, I was using an aggressiveness of one or unity, values over that seemed to cause the guiding to oscillate and cause all manner of mischief.

HTH,
Doug
Reply With Quote
  #9  
Old 18-07-2006, 12:43 PM
EzyStyles's Avatar
EzyStyles (Eric)
I HATE COMA!

EzyStyles is offline
 
Join Date: Jan 2006
Location: Melbourne, Victoria
Posts: 3,208
Quote:
Originally Posted by avandonk
You are at a very high mag. First establish which direction the stars are elongated. My bet is in declination. Overcorrection can lead to this problem.

Bert
Cheers Bert. The stars are actually elongated everywhere from top left to bottom right. They are not elongated from just one direction eg dec.

very strange.
Reply With Quote
  #10  
Old 18-07-2006, 12:45 PM
EzyStyles's Avatar
EzyStyles (Eric)
I HATE COMA!

EzyStyles is offline
 
Join Date: Jan 2006
Location: Melbourne, Victoria
Posts: 3,208
Quote:
Originally Posted by Doug
G'day Eric, I tend to agree with Bert. You seem to have dec drift and this is most likely caused by incorrect dec backlash compensation, and also perhaps, too long a time interval between guide corrections.
The other image unguided that you linked to is the result of out of balance OTA I believe. And that might be part of your current problem as well. It would be interesting to know what your guide exposure time is? Not sure what you mean by 'guide speed=.25. Is that aggressiveness or guide exposure time? Not sure what you mean by RA backlash. Guide corrections for RA typically either speed up the drive, slow it down or maybe even stop it briefly. It is not usual to actually reverse direction of RA, so backlash would not be an issue. Depending on the brightness of your guide star, you might find guide exosures of 2 to 8 seconds should work well for you. From Memory, I was using an aggressiveness of one or unity, values over that seemed to cause the guiding to oscillate and cause all manner of mischief.

HTH,
Doug
Cheers doug. oh my guide speed is the speed that the EQ6 is set to when guiding. my guide exposures are 1 sec. i'll go and recheck my ota balancing.
thanks.
Reply With Quote
  #11  
Old 18-07-2006, 02:51 PM
JohnH's Avatar
JohnH
Member # 159

JohnH is offline
 
Join Date: Feb 2005
Location: NSW
Posts: 1,226
I am on this journey too...

I have found the source of and treatment of DEC and RA tracking errors to be different, I suggest therefore that you try this, polar align as best you can and turn DEC corrections off. Adjust your guiding params to get good RA compensation. Now turn on DEC comp but only in one direction (opposite your residual drift).

You do not need good skies to practice this stuff so don't wait for perfect conditions....
Reply With Quote
  #12  
Old 19-07-2006, 02:48 PM
EzyStyles's Avatar
EzyStyles (Eric)
I HATE COMA!

EzyStyles is offline
 
Join Date: Jan 2006
Location: Melbourne, Victoria
Posts: 3,208
Cheers John. Will give that a shot. How would I turn DEC corrections off?
Reply With Quote
  #13  
Old 19-07-2006, 03:10 PM
JohnH's Avatar
JohnH
Member # 159

JohnH is offline
 
Join Date: Feb 2005
Location: NSW
Posts: 1,226
It depends on your guiding software. I do not know envisage's guiding capabilites but if you cannot disable there then you might be able to stop the signal getting to the mount at either the Shoestring adapter or the virtual LX200 s'ware.
Reply With Quote
  #14  
Old 19-07-2006, 07:01 PM
EzyStyles's Avatar
EzyStyles (Eric)
I HATE COMA!

EzyStyles is offline
 
Join Date: Jan 2006
Location: Melbourne, Victoria
Posts: 3,208
thanks John. just had a look at the software dont think you can just disable one unless i rewire the autoguiding cable? Ill have a good look at it.
Reply With Quote
Reply

Bookmarks


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 01:37 AM.

Powered by vBulletin Version 3.8.7 | Copyright ©2000 - 2025, Jelsoft Enterprises Ltd.
Advertisement
Bintel
Advertisement
Astrophotography Prize
Advertisement