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

Reply
 
Thread Tools Rate Thread
  #21  
Old 24-01-2014, 02:36 PM
alistairsam's Avatar
alistairsam
Registered User

alistairsam is offline
 
Join Date: Nov 2009
Location: Box Hill North, Vic
Posts: 1,817
Quote:
Originally Posted by SkyViking View Post
Interesting thread. I usually experience between 2" and 3". I have seen below 2" on occasion, but it's rare. If it's over 3" I switch to taking colour, binned 2x2. I rarely see it higher than 3.5-4" though (only on a few nights per year).
Hi Rolf,

I'm a bit curious about this. what software did you use for the above measurements?
I'm struggling with constant above 4 FWHM as reported by Maxim, ccdstack and ccdinspector but I thought it could be my guiding/mount performance/scope rigidity all of which could smear the stars over a few pixels increasing the overall fwhm. I use an OAG with the lodestar and guiding is pretty flat.
I constantly get blurred images, with my F4 I get pretty good details, but compared to others, its blurred.
I even tried with a refractor, but ended up with 3.9.
would this mean that this is basically due to poor seeing?
if it is, then I'm moving to the hills.

Cheers
Alistair
Reply With Quote
  #22  
Old 24-01-2014, 07:57 PM
SkyViking's Avatar
SkyViking (Rolf)
Registered User

SkyViking is offline
 
Join Date: Aug 2009
Location: Waitakere Ranges, New Zealand
Posts: 2,260
Hi Alistair,

Here is an example of a good night at my site, FWHM ~2":
http://www.rolfolsenastrophotography...g/i-bNVbbNZ/X3
That is measured with PixInsight. I get similar results in Maxim for the same frame, so expect it to be reasonably accurate.

First of all I'd suspect that your image scale is set incorrectly so FWHM is not reported properly, but if you say images are also blurred compared to others then maybe not. Just something to double-check.
And secondly, collimation could be off.

I don't know if your site has particularly poor seeing. If it's always 4 or above then that sounds odd, but I'm really just guessing
What is the experience of others in your area?

Cheers,
Rolf
Reply With Quote
  #23  
Old 24-01-2014, 09:41 PM
Geoff45's Avatar
Geoff45 (Geoff)
PI rules

Geoff45 is offline
 
Join Date: Jul 2006
Location: Sydney
Posts: 2,413
I throw out everything over 3" fwhm in luminance, over 3.5" in colour.
Geoff.
Reply With Quote
  #24  
Old 24-01-2014, 10:28 PM
SkyViking's Avatar
SkyViking (Rolf)
Registered User

SkyViking is offline
 
Join Date: Aug 2009
Location: Waitakere Ranges, New Zealand
Posts: 2,260
Tonight's seeing is pretty good here, below 2" in both axes: FWHMx 1.9" and FWHMy 1.7"
I'm currently making the most of it but my target will go behind trees in about 10 mins. And the Moon is also coming up soon... I think it's time to go to bed
Attached Thumbnails
Click for full-size image (FWHM-good-NGC3576_web.jpg)
201.3 KB54 views
Reply With Quote
  #25  
Old 24-01-2014, 11:21 PM
alistairsam's Avatar
alistairsam
Registered User

alistairsam is offline
 
Join Date: Nov 2009
Location: Box Hill North, Vic
Posts: 1,817
Quote:
Originally Posted by SkyViking View Post
Tonight's seeing is pretty good here, below 2" in both axes: FWHMx 1.9" and FWHMy 1.7"
Officially jealous...
Reply With Quote
  #26  
Old 25-01-2014, 11:27 PM
White Rabbit's Avatar
White Rabbit
Space Cadet

White Rabbit is offline
 
Join Date: Feb 2007
Location: Sydney
Posts: 1,409
Quote:
Originally Posted by alistairsam View Post
Officially jealous...
Yip, me to. Forget about the quality of seeing, I'd settle for a clear sky. We've had clouds for weeks now. Next week looks promising though.
Reply With Quote
  #27  
Old 04-03-2014, 05:26 PM
Gem's Avatar
Gem (Grant)
The serenity...

Gem is offline
 
Join Date: Mar 2011
Location: Canberra, Australia
Posts: 925
Quote:
Originally Posted by Logieberra View Post
Peter, how do our TheSkyX HalfFluxDiameter HFD figures correspond to FWHM? The same? If so, in the burbs of Canberra, I never see below 3. Evenings start at mid 5's and get marginally better over time.
With the ATIK and 80mm, I can get down to 1.6 late at night in Canberra on a good night. No hope earlier in the evening or with the SCT. Usually around 2-3 earlier in the evenings on good nights.
Reply With Quote
  #28  
Old 04-03-2014, 07:10 PM
Logieberra's Avatar
Logieberra (Logan)
Registered User

Logieberra is offline
 
Join Date: Mar 2010
Location: Canberra
Posts: 1,546
Funny you say that, Grant. I ran an experiment shortly after my post, above, last September. I found that my Kendrick dew controller heater strap was ruining my focus! Bumped the heater settings way down and saw instant results, with HFDs in high 1s and 2s!
Reply With Quote
  #29  
Old 04-03-2014, 09:32 PM
Gem's Avatar
Gem (Grant)
The serenity...

Gem is offline
 
Join Date: Mar 2011
Location: Canberra, Australia
Posts: 925
Quote:
Originally Posted by Logieberra View Post
Funny you say that, Grant. I ran an experiment shortly after my post, above, last September. I found that my Kendrick dew controller heater strap was ruining my focus! Bumped the heater settings way down and saw instant results, with HFDs in high 1s and 2s!
No coincidence that my SCT usually uses a dew heater then!
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 10:30 AM.

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