#1  
Old 18-02-2018, 01:28 PM
SimmoW's Avatar
SimmoW (SIMON)
Farting Nebulae

SimmoW is offline
 
Join Date: Jan 2014
Location: Tamleugh, Victoria, Australia
Posts: 1,333
Dark Sky comparison from Tamleugh

Hope this is in the right forum, imho this is the most important equipment of all!

Just in case you were wondering whether dark skies were beneficial for even narrowband imaging...

https://youtu.be/e6eReQVXi4k
Reply With Quote
  #2  
Old 18-02-2018, 02:15 PM
RickS's Avatar
RickS (Rick)
PI cult recruiter

RickS is offline
 
Join Date: Apr 2010
Location: Brisbane
Posts: 10,582
Not sure that the stretching has been adjusted to make a fair comparison, Simon? The stars in the dark sky image are quite a bit larger and my guess is that it's mainly due to a bigger stretch.

Just playing devil's advocate I would expect better results, of course.

Cheers,
Rick.
Reply With Quote
  #3  
Old 18-02-2018, 03:02 PM
SimmoW's Avatar
SimmoW (SIMON)
Farting Nebulae

SimmoW is offline
 
Join Date: Jan 2014
Location: Tamleugh, Victoria, Australia
Posts: 1,333
Thats ok rick. I'll triple check later, but when we reviewed the subs together the tamleugh subs did indeed have larger stars due to the wind gusts that night. So the night after that was dead-still, would have shown even greater differences
Reply With Quote
  #4  
Old 18-02-2018, 03:13 PM
RickS's Avatar
RickS (Rick)
PI cult recruiter

RickS is offline
 
Join Date: Apr 2010
Location: Brisbane
Posts: 10,582
Thanks, Simon.
Reply With Quote
  #5  
Old 18-02-2018, 03:16 PM
Slawomir's Avatar
Slawomir (Suavi)
Amateur Photon Collector

Slawomir is offline
 
Join Date: Sep 2014
Location: Proserpine
Posts: 2,988
There is a stark difference between the two. Thank you Simon for sharing. Darker skies will surely allow for capturing fainter bits more quickly.

Speaking of dark skies, I'm really curious and itching to get my gear out at our new much darker location, comparing to Paddington at least. In spite of four! nearby street lights, I can easily see (without a telescope) Magellanic Clouds, MW and some features within the MW - huge improvement over yellow city night sky I have been accustomed to. I need to wait patiently for a drier weather though.
Reply With Quote
  #6  
Old 18-02-2018, 05:08 PM
SimmoW's Avatar
SimmoW (SIMON)
Farting Nebulae

SimmoW is offline
 
Join Date: Jan 2014
Location: Tamleugh, Victoria, Australia
Posts: 1,333
Ooh that does sound promising Slawomir, if you can see the 'clouds' thatll be a good improvement in contrast
Reply With Quote
  #7  
Old 18-02-2018, 07:47 PM
Peter Ward's Avatar
Peter Ward
Galaxy hitchhiking guide

Peter Ward is offline
 
Join Date: Dec 2007
Location: The Shire
Posts: 6,631
Seeing and transparency have not been quantified here.

With a 5nm (or less) bandpass filter, even with a full moon, I have been challenged to find any benefit in a dark site.

Sorry...I don't agree that the sample data of two, as shown here, is a definite proof.
Reply With Quote
  #8  
Old 18-02-2018, 09:05 PM
SimmoW's Avatar
SimmoW (SIMON)
Farting Nebulae

SimmoW is offline
 
Join Date: Jan 2014
Location: Tamleugh, Victoria, Australia
Posts: 1,333
Getting some more samples soon Peter. Not sure if seeing would make much difference? The suburban subs had much better fwhm. Maybe others can chime in. Not sure of any other similar tests before, esp with exactly the same equipment.
Reply With Quote
  #9  
Old 18-02-2018, 10:03 PM
Peter Ward's Avatar
Peter Ward
Galaxy hitchhiking guide

Peter Ward is offline
 
Join Date: Dec 2007
Location: The Shire
Posts: 6,631
Quote:
Originally Posted by SimmoW View Post
Getting some more samples soon Peter. Not sure if seeing would make much difference? The suburban subs had much better fwhm. Maybe others can chime in. Not sure of any other similar tests before, esp with exactly the same equipment.
Seeing is king.

Fainter stars and nebulosity are patently visible on nights of good seeing and transparency.

The narrower bandpass, the less the effect of skyglow. (this is why sub-angstrom Solar filters work so well)

What bandpass are you using? (not stated in the video)

I'd expect to see a minor difference at say, 12nm, but not at 5nm or 3nm
Reply With Quote
  #10  
Old 19-02-2018, 05:48 AM
Slawomir's Avatar
Slawomir (Suavi)
Amateur Photon Collector

Slawomir is offline
 
Join Date: Sep 2014
Location: Proserpine
Posts: 2,988
I used to observe a significant drop in background ADU in Paddington as the city was slowly going to sleep. Also, when there was a game on in nearby stadium, SNR would really suffer, not to mention neighbours turning lights on. That was with 3nm Astrodons. Moon of course had a significant impact too.

I’m yet to take my rig out at the new location, but I would be really surprised if I won’t be picking up fainter nebulosities much quicker, as the skies here are quite dark.

Apart from the amount of sky glow, seeing of course also play a key role but I think Simon’s compo was focused on illustrating of the former.

In any case, stars are bloated in the image taken at the darker site, so seeing was probably worse over there on that night, which wouldn’t help the data, yet clearly more nebulosity is visible.

My 2 cents.
Reply With Quote
  #11  
Old 19-02-2018, 07:01 AM
SimmoW's Avatar
SimmoW (SIMON)
Farting Nebulae

SimmoW is offline
 
Join Date: Jan 2014
Location: Tamleugh, Victoria, Australia
Posts: 1,333
Thanks for the further 'evidence' Slawomir. Yes its the contrast and adu value increasesi was trying to illustrate.

Peter, i'll add more into the video.they were 3nm Astrodons.

Maybe you could sponsor a full dark sky comparison study? 2 exactly matchind sets of Officina Stellare RH300 scopes and MX+ mounts with full frame FLI cameras. Happy to host!
Reply With Quote
  #12  
Old 19-02-2018, 08:11 AM
RickS's Avatar
RickS (Rick)
PI cult recruiter

RickS is offline
 
Join Date: Apr 2010
Location: Brisbane
Posts: 10,582
Simon, shouldn't you be getting ADU value decreases at the dark site? That's the benefit... no additive light pollution. The decrease will be most pronounced in the background areas, of course, leading to the increase in contrast that you mentioned. That's why I think the video is misleading. The dark site data shouldn't look brighter (for a fair comparison) but it should look most contrasty.

Cheers,
Rick.
Reply With Quote
  #13  
Old 19-02-2018, 09:28 AM
SimmoW's Avatar
SimmoW (SIMON)
Farting Nebulae

SimmoW is offline
 
Join Date: Jan 2014
Location: Tamleugh, Victoria, Australia
Posts: 1,333
My bad rick, i meant a relative increase in the target adu signal.

The screen recording software, then youtube then fb all change the final video exposures! You should have seen how many different screen recorders i had to try before settling on the least invasive.

I will load up the original fits files soon for pure blinking comparison
Reply With Quote
  #14  
Old 19-02-2018, 09:57 AM
RickS's Avatar
RickS (Rick)
PI cult recruiter

RickS is offline
 
Join Date: Apr 2010
Location: Brisbane
Posts: 10,582
Quote:
Originally Posted by SimmoW View Post
My bad rick, i meant a relative increase in the target adu signal.

The screen recording software, then youtube then fb all change the final video exposures! You should have seen how many different screen recorders i had to try before settling on the least invasive.

I will load up the original fits files soon for pure blinking comparison
If you have a few calibrated FITS files I'd be happy to run some stats for you.
Reply With Quote
  #15  
Old 19-02-2018, 10:00 AM
SimmoW's Avatar
SimmoW (SIMON)
Farting Nebulae

SimmoW is offline
 
Join Date: Jan 2014
Location: Tamleugh, Victoria, Australia
Posts: 1,333
Thanks Rick. For now all I have is Uri's best raw Ha subs, link here:

https://drive.google.com/open?id=1HR...rGJN-fvHOmB9kn
Reply With Quote
  #16  
Old 19-02-2018, 04:25 PM
SimmoW's Avatar
SimmoW (SIMON)
Farting Nebulae

SimmoW is offline
 
Join Date: Jan 2014
Location: Tamleugh, Victoria, Australia
Posts: 1,333
oh and the comparison files and video is OIII, not Ha. Sh308 bubble is predominant in OIII. And most susceptible to light pollution from what I hear.
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 04:24 PM.

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