#1  
Old 15-08-2019, 10:44 PM
RyanJones
Registered User

RyanJones is offline
 
Join Date: Jun 2018
Location: Melbourne,Australia
Posts: 1,439
C9.25 Guiding Test

I decided to take the opportunity while the moon is around to bolt my guide setup on top of my 9.25 SCT and do some guiding tests. To aid the short focal length guider I also added a .63 focal reducer to bring the focal length of the SCT down to a more palatable 1500mm. Still a stretch for a 400mm guider but that was what the test set out to prove. So here is my result ;

Celestron C9.25 w/ 0.63 focal reducer
60 x 180sec subs + 10 darks
Canon 350d astromodified @ iso 800
STC Duo Filter
Sky-Watcher 80/400 guide scope w/ Nexguide SAG
HEQ5 pro
Bortle 8 skies w/ 98% moon

Image cropped for asthetics
Attached Thumbnails
Click for full-size image (828B2C93-D24D-4AC9-8BDD-CD4665B5D2A9.jpeg)
176.0 KB57 views
Reply With Quote
  #2  
Old 16-08-2019, 01:02 AM
billdan's Avatar
billdan (Bill)
Registered User

billdan is offline
 
Join Date: Mar 2012
Location: Narangba, SE QLD
Posts: 1,551
The stars at the bottom of the image look very good, the stars at the top look a bit elliptical (which could be collimation or camera tilt).
The stars in the centre have halo's around them which points to some dew on the corrector plate.

The pillars of creation came out well and with a few more subs you could get more detail in them.

Reply With Quote
  #3  
Old 16-08-2019, 05:45 AM
xelasnave's Avatar
xelasnave
Gravity does not Suck

xelasnave is offline
 
Join Date: Mar 2005
Location: Tabulam
Posts: 16,866
It looks as if the guiding is ok and I agree with Bill on his explanation of the other aspects. It will be interesting to how the new combo works in the future.
Well done.

alex
Reply With Quote
  #4  
Old 16-08-2019, 07:49 AM
The_bluester's Avatar
The_bluester (Paul)
Registered User

The_bluester is offline
 
Join Date: Feb 2011
Location: Kilmore, Australia
Posts: 3,342
I have used my C925 a reasonable amount for AP, what I did find very beneficial was using an off axis guider. So far off the centre of the FOV the guide stars look terrible but it works.

I did find that any sort of focus activity and a large enough change in pointing showed up as mirror movement but I don't know if that would end up relating to having to toss out the occasional sub or having movement visible in lots of subs.
Reply With Quote
  #5  
Old 16-08-2019, 09:21 AM
RyanJones
Registered User

RyanJones is offline
 
Join Date: Jun 2018
Location: Melbourne,Australia
Posts: 1,439
Thank you for your input guys.

The Halos are from over excited processing in the star reduction phase rather than dew or dust. I see the tilt though. This doesn’t surprise me as I sometimes have similar issues when using my Newt. I think to help this I’m going to reduce the weight of the camera by moving the remote intervelometer from the hot shoe to my distribution box and just run another cable to the camera.

Re: OAG, I’ve been reluctant to go down this path because honestly I don’t know how well the Nexguide will handle it. It’s pretty fussy with the brightness of stars and is really quite sensitive to focus. Given that it only gives me a digital representation of stars rather than an image, I think it might be quite hard to get right. I agree though that OAG is the ideal way to go for such long focal lengths.
Reply With Quote
  #6  
Old 17-08-2019, 07:53 AM
LostInSp_ce's Avatar
LostInSp_ce
Unregistered User

LostInSp_ce is offline
 
Join Date: Mar 2017
Posts: 754
Ryan I had a similar problem to yours show up in my images when I was testing things earlier on in the year and found it to be tilt from the rotator which hadn't been tightened fully. So maybe do a close inspection of all your contact points to see if anything has come loose or is flexing under load.
Reply With Quote
  #7  
Old 17-08-2019, 10:49 AM
RyanJones
Registered User

RyanJones is offline
 
Join Date: Jun 2018
Location: Melbourne,Australia
Posts: 1,439
Quote:
Originally Posted by LostInSp_ce View Post
Ryan I had a similar problem to yours show up in my images when I was testing things earlier on in the year and found it to be tilt from the rotator which hadn't been tightened fully. So maybe do a close inspection of all your contact points to see if anything has come loose or is flexing under load.
Thank you for the suggestion. When you say “ rotator “ what part is that exactly ? I will check that all mounting parts are tight though. Cheers
Reply With Quote
  #8  
Old 17-08-2019, 11:42 AM
LostInSp_ce's Avatar
LostInSp_ce
Unregistered User

LostInSp_ce is offline
 
Join Date: Mar 2017
Posts: 754
My problem with the rotator was on a refractor but you may not have one on your Newt. Even so your setup is not immune from possible tilt. Check all connections around your imaging train e.g focuser, camera, spacers, filters anything that connects via threads, compression rings e.t.c. Also keep an eye out for any cable tugs that could be happening to your camera as the mount slews around from one position to another.
Reply With Quote
  #9  
Old 17-08-2019, 12:55 PM
RyanJones
Registered User

RyanJones is offline
 
Join Date: Jun 2018
Location: Melbourne,Australia
Posts: 1,439
Quote:
Originally Posted by LostInSp_ce View Post
My problem with the rotator was on a refractor but you may not have one on your Newt. Even so your setup is not immune from possible tilt. Check all connections around your imaging train e.g focuser, camera, spacers, filters anything that connects via threads, compression rings e.t.c. Also keep an eye out for any cable tugs that could be happening to your camera as the mount slews around from one position to another.
I’ll check all of my fittings next time I’m out and see if I can find any areas of flex. Reducing the weight of the camera can’t hurt though for both setups as if there is any room for movement, the less weight, the less likely it is to occur. Thank you again for you advice
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 01:32 AM.

Powered by vBulletin Version 3.8.7 | Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Advertisement
Testar
Advertisement
Bintel
Advertisement