ICEINSPACE
Most Read Articles
Moon Phase
CURRENT MOON Waning Gibbous
76.1%
The Sun Now
Time Zones
Sydney*
9:07 am
Perth
6:07 am
Auckland*
11:07 am
New York
5:07 pm
Paris
11:07 pm
GMT
10:07 pm




Go Back   IceInSpace > Equipment > Astrophotography and Imaging Equipment and Discussions

Reply
 
Thread Tools Rate Thread
  #1  
Old 16-10-2017, 12:26 PM
Andy01's Avatar
Andy01 (Andy)
My God it's full of stars

Andy01 is offline
 
Join Date: Mar 2012
Location: Melbourne
Posts: 2,013
Guiding an RC at 1500mm - best PHD settings... (Update below - thoughts?)

Got a new GSO CF RC8 on Friday and gave it a test run on the weekend.

On Sat arvo, a mate collimated it for me with a TAK microscope thingy, and CCD inspector says it looks pretty good, with a minor tilt issue that will take time to resolve until the bog standard, (substandard) focusser is upgraded.

... and I discovered that urgently need to source a dew heater for the secondary!

However, despite my PA being spot on as per my usual methods - I noted that my PHD graph was up and down like a kids birthday party at Bounce!

It's normally a pretty flat line, (as in the patient's dead doctor...) I'm using a QSI 683 with a Lodestar OAG on an EQ6.

So does anyone have recommended settings for PHD at longer Focal Lengths? (I use PHD 1 - original flavour)

Cheers

Andy

UPDATE 18/10 : See thread below...
Attached Thumbnails
Click for full-size image (Screen Shot 2017-10-16 at 1.21.29 PM.png)
124.1 KB90 views
Click for full-size image (RC8.jpg)
41.2 KB56 views
Click for full-size image (1365.jpg)
210.0 KB74 views

Last edited by Andy01; 18-10-2017 at 09:06 AM. Reason: updated
Reply With Quote
  #2  
Old 16-10-2017, 01:17 PM
Octane's Avatar
Octane (Humayun)
IIS Member #671

Octane is offline
 
Join Date: Dec 2005
Location: Canberra
Posts: 11,156
Were you getting round stars?

H
Reply With Quote
  #3  
Old 16-10-2017, 02:24 PM
glend (Glen)
Registered User

glend is offline
 
Join Date: Jun 2013
Location: Lake Macquarie, NSW
Posts: 4,956
That is a pretty light scope, have you got a bit of weight on to make it east heavy? NEQ6s like abit of weight. I used to add weight to the front of my RC08 to better balance the imaging gear, its a bit bum heavy orherwise.
Did you run the Guide Assistant? I would do that and accept the recommended settings and see if it gets better.
I would upgrade to PHD2.

Kendrick Astro make a very nice secondary heater for the RC08, it comes with thin copper tape that you can use instead of wire to run across the spider vanes.
Reply With Quote
  #4  
Old 16-10-2017, 03:08 PM
luka's Avatar
luka
Unregistered User

luka is offline
 
Join Date: Apr 2007
Location: Perth, Australia
Posts: 1,040
Andy, seen this post? It may have a few useful tips.
Reply With Quote
  #5  
Old 16-10-2017, 03:31 PM
Andy01's Avatar
Andy01 (Andy)
My God it's full of stars

Andy01 is offline
 
Join Date: Mar 2012
Location: Melbourne
Posts: 2,013
Quote:
Originally Posted by Octane View Post
Were you getting round stars?

H
Hi H, yes except in the bottom right cnr - I've just added a LUM test pic of NGC 1365 from Sat night.

Quote:
Originally Posted by glend View Post
I used to add weight to the front of my RC08 to better balance the imaging gear, its a bit bum heavy orherwise.
Did you run the Guide Assistant? I would do that and accept the recommended settings and see if it gets better.
I would upgrade to PHD2.

Kendrick Astro make a very nice secondary heater for the RC08,
Thanks Glen, I'll try that, as I've not used PHD2 - also who supplies that Kendrick unit?

Quote:
Originally Posted by luka View Post
Andy, seen this post? It may have a few useful tips.
Yes Luka, read with great interest!
Reply With Quote
  #6  
Old 16-10-2017, 03:45 PM
glend (Glen)
Registered User

glend is offline
 
Join Date: Jun 2013
Location: Lake Macquarie, NSW
Posts: 4,956
Kendrik Astro supplies them. Not hard to find.

http://www.kendrickastro.com/rcoptics.html
Reply With Quote
  #7  
Old 16-10-2017, 03:58 PM
Andy01's Avatar
Andy01 (Andy)
My God it's full of stars

Andy01 is offline
 
Join Date: Mar 2012
Location: Melbourne
Posts: 2,013
Quote:
Originally Posted by glend View Post
Kendrik Astro supplies them. Not hard to find.

http://www.kendrickastro.com/rcoptics.html
Sorry mate, should have specified in Australia - I was hoping to source one for the star party at Nhill this weekend.
Reply With Quote
  #8  
Old 16-10-2017, 04:10 PM
gregbradley's Avatar
gregbradley
Registered User

gregbradley is offline
 
Join Date: Feb 2006
Location: Sydney
Posts: 14,870
Longer focal lengths may show more up and downs in PHD. You've been using a very short focal length scope so the bumps up and down with the pE would be a smaller angular distance than a 1600mm focal length.

Your attached image shows round stars so there is no problem. The elongated stars at the lower part of the image are tilt issues not guiding. I have made that mistake before, trying to correct guiding when it was tilt.

Your CCD Inspector graph shows heavy tilt so I would try to pack out the offending side (probably the top of your camera looking at it from behind the scope).

Greg.
Reply With Quote
  #9  
Old 16-10-2017, 06:26 PM
peter_4059's Avatar
peter_4059 (Peter)
Big Scopes are Cool

peter_4059 is offline
 
Join Date: Jun 2007
Location: Brisbane
Posts: 3,979
OSC index looks quite low. Perhaps try increasing RA aggressiveness.
Reply With Quote
  #10  
Old 16-10-2017, 07:20 PM
DJT (David)
Registered User

DJT is offline
 
Join Date: Nov 2011
Location: Sydney
Posts: 1,305
Quote:
Originally Posted by Andy01 View Post
Sorry mate, should have specified in Australia - I was hoping to source one for the star party at Nhill this weekend.
Hi Andy
Bintel has them. Check under dew control under the accessories tab
Reply With Quote
  #11  
Old 16-10-2017, 07:48 PM
DiscoDuck's Avatar
DiscoDuck (Paul)
Raider Nation

DiscoDuck is offline
 
Join Date: Apr 2014
Location: Adelaide
Posts: 335
Not sure what units PHD's RMS is in there, Andy. But if arcsec, then I'd be happy with the 0.56 you're getting!

Even if that's pixels of the Lodestar (which I suspect it might be for PHD1 - I use PHD 2), that's probably still around 0.6-0.65", which seems still OK for an EQ6.

I also have an EQ6 (and an RC8) and on a great night (very rare!) I get around 0.5" RMS for periods. Typically it's more in the 0.6 to 0.7" range for a good to medium night. And can easily push higher than that with anything more than a gentle breeze.

And when backlash rears its ugly head with a nasty gust of wind or two, it can be many arcseconds!!
Reply With Quote
  #12  
Old 18-10-2017, 09:02 AM
Andy01's Avatar
Andy01 (Andy)
My God it's full of stars

Andy01 is offline
 
Join Date: Mar 2012
Location: Melbourne
Posts: 2,013
Update

Ran a test at home last night, several hrs later, I finally got decent guiding.

Tried various amounts of RA aggression, these settings performed best on my EQ6.

Not sure if the seeing was bad as it was quite warm outside so maybe that affected it? This sub was taken at zenith.

Still some evidence of tilt though.

Gonna have to get a feathertouch and the tilt adjuster plate before getting serious with this thing!
Attached Thumbnails
Click for full-size image (PHD RC8 settings.jpg)
70.7 KB55 views
Click for full-size image (RC8 final test.png)
114.9 KB35 views
Click for full-size image (253_GSOx10min-LUM_iis.jpg)
193.6 KB59 views
Reply With Quote
  #13  
Old 18-10-2017, 09:17 AM
glend (Glen)
Registered User

glend is offline
 
Join Date: Jun 2013
Location: Lake Macquarie, NSW
Posts: 4,956
Did you get the optional focuser collimation ring with your scope? The RC08 is known to need these things. Have you checked with a laser to see if your focuser is aligned to the secondary centre spot? The collimation ring allows you to setup the focuser correctly. Of course you could buy a new focuser but the ring is a much cheaper option. I think Andrews and Bintel have them.
Reply With Quote
  #14  
Old 18-10-2017, 10:00 AM
Andy01's Avatar
Andy01 (Andy)
My God it's full of stars

Andy01 is offline
 
Join Date: Mar 2012
Location: Melbourne
Posts: 2,013
Quote:
Originally Posted by glend View Post
Did you get the optional focuser collimation ring with your scope? The RC08 is known to need these things. Have you checked with a laser to see if your focuser is aligned to the secondary centre spot? The collimation ring allows you to setup the focuser correctly. Of course you could buy a new focuser but the ring is a much cheaper option. I think Andrews and Bintel have them.
Already did the laser focusser check with a Cheshire as best we could at the same time as we collimated the scope with the TAK Microscope, but will do it again after the following upgrades are aquired next month...

Looks like I'll have to order the following...

- Tilt adjustment ring (from Andrew's)
- Secondary dew heater from (Kendrick: Canada - Bintel is out of stock)
- Feathertouch Focusser & adapter (from the USA)
- Losmandy weights (no idea where from as yet)

I'm used to imaging with refractors straight out of the box, so this is a new challenge - all good fun! Will sort it out eventually and those galaxies arn't going anywhere soon
Reply With Quote
  #15  
Old 18-10-2017, 10:01 AM
xelasnave's Avatar
xelasnave
Gravity does not Suck

xelasnave is offline
 
Join Date: Mar 2005
Location: Tabulam
Posts: 11,158
Congratulations on your new scope Andy and good luck with setting it all up.
alex
Reply With Quote
  #16  
Old 18-10-2017, 10:05 AM
xelasnave's Avatar
xelasnave
Gravity does not Suck

xelasnave is offline
 
Join Date: Mar 2005
Location: Tabulam
Posts: 11,158
Are you aware these scopes may need time to reach thermal equilibrium?
I dont know what it may be here but coming from refractors this may be an aspect to consider..I can imagine you wanting to get out there for some results so just maybe???
alex
Reply With Quote
  #17  
Old 18-10-2017, 10:38 AM
Andy01's Avatar
Andy01 (Andy)
My God it's full of stars

Andy01 is offline
 
Join Date: Mar 2012
Location: Melbourne
Posts: 2,013
Quote:
Originally Posted by xelasnave View Post
Are you aware these scopes may need time to reach thermal equilibrium?
alex
Yes thanks Alex, I was out there until Midnight and I think during that time the focus did move a tad, although it's a CF tube. All the more reason for a decent focusser as my QSI 683 camera is VERY heavy.
Reply With Quote
  #18  
Old 18-10-2017, 11:28 AM
Camelopardalis's Avatar
Camelopardalis (Dunk)
Drifting from the pole

Camelopardalis is offline
 
Join Date: Feb 2013
Location: Brisbane
Posts: 4,411
Certainly looks promising Andy great test subs.
Reply With Quote
  #19  
Old 18-10-2017, 01:25 PM
DJT (David)
Registered User

DJT is offline
 
Join Date: Nov 2011
Location: Sydney
Posts: 1,305
Quote:
Originally Posted by Camelopardalis View Post
Certainly looks promising Andy great test subs.
Agreed, getting closer.
Reply With Quote
  #20  
Old 24-10-2017, 02:37 PM
Moon's Avatar
Moon (James)
This sentence is false

Moon is offline
 
Join Date: Oct 2008
Location: Melbourne
Posts: 1,147
Andy
I've used a similar combo (EQ6 + PHD + GSO RC8) and the guiding can be tricky! Some nights just a small amount of wind can cause huge problems. Also depending on where you are in the sky as well - some areas of the sky seem to guide better than others. And some nights guiding is terrible for no apparent reason - cable snags, balance, poor gear mesh etc etc.
There are some images on my site with this combo you can view here: https://deepspaceplace.com/images.ph...&filter=GSO8RC

Most are on the EQ6 but some are on the PME - it's noted on each image. All with the stock focuser. A flattener might be a good investment for you.

My advice for PHP and collimation is to keep doing what you are doing - stick at it. Make small adjustments, make notes, check, measure etc and you will dial in the best results possible within the limits of your gear and all the other factors. I think this focal length is pushing the EQ6 to the max IMHO.

Also this might help https://deepspaceplace.com/gso8rccollimate.php

Cheers
James
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 08:07 AM.

Powered by vBulletin Version 3.8.7 | Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.
Advertisement
NexDome Observatories
Advertisement
SkyWatcher 2018 Catalogue
Advertisement
FLI Cameras and Imaging Accessories
Advertisement
Bintel
Advertisement
Interest Free Finance
Advertisement
SkyWatcher WiFi Adaptor
Advertisement
OzScopes Authorised Dealer
Advertisement
Lunatico Astronomical
Advertisement
Astronomy and Electronics Centre
Advertisement