#1  
Old 13-09-2021, 07:59 PM
N1 (Mirko)
Registered User

N1 is offline
 
Join Date: Oct 2013
Location: Dunners Nu Zulland
Posts: 1,661
Venus

My first auccessful attempt at recording cloud detail on Venus (i.e. where I'm actually confident it's not artefacts I'm seeing), yet it was just an afterthought during a visual observing session this afternoon with the old untracked 8" dob. With the weather closing in, there was no time to set up anything else, so this was done with a guide cam, manually tracked. Still a far cry from what we've been seeing on here recently but I'm happy with the result of this impromptu imaging "session"

Good practice for processing better data later on too

8" GSO dob with TMB1.8x ED barlow, ASI120MM, Venus U and Pro Planet IR742. Side observation: The TMB ED barlow passes significantly more UV signal and has significantly less scatter and internal reflections in the UV than the GSO ED barlow, which I realised today is essentially useless for this task.
Attached Thumbnails
Click for full-size image (Venus 210913 UVIR label.jpg)
61.3 KB57 views
Reply With Quote
  #2  
Old 14-09-2021, 07:38 AM
multiweb's Avatar
multiweb (Marc)
ze frogginator

multiweb is offline
 
Join Date: Oct 2007
Location: Sydney
Posts: 22,060
Nice. You clearly did get cloud patterns in the UV. Hard yakka with a 8" and shortish FL. Good point about the barlow. Never thought about it. I'll have to read up on mine see if ut has any kind UV/IR block coatings. That would be a bummer. Probably why it's best to use a long FL native system with a large aperture and no glass in the light path if possible.
Reply With Quote
  #3  
Old 14-09-2021, 01:28 PM
N1 (Mirko)
Registered User

N1 is offline
 
Join Date: Oct 2013
Location: Dunners Nu Zulland
Posts: 1,661
Thanks Marc, I think your barlow definitely works better than my GSO going by those great results you've been getting. I was looking at fused silica negative achromats to make my own but now I think I'll have a play with the TMB's spacing to get more amplification out of it first. That might be all that's needed, especially on the RC. The dob's infocus probably won't allow much of that. It's also why I wasn't able to use my de-windowed regular ASI120MM with the barlow. I was able to compare both cams at prime focus though, and found that with the AR window in place, required exposure times increased about 4-fold (!).
Reply With Quote
  #4  
Old 14-09-2021, 01:36 PM
multiweb's Avatar
multiweb (Marc)
ze frogginator

multiweb is offline
 
Join Date: Oct 2007
Location: Sydney
Posts: 22,060
Quote:
Originally Posted by N1 View Post
Thanks Marc, I think your barlow definitely works better than my GSO with those great results you've been getting. I was looking at fused silica negative achromats to make my own but now I think I'll have a play with the TMB's spacing to get more amplification out of it first. That might be all that's needed, especially on the RC. The dob's infocus probably won't allow much of that. It's also why I wasn't able to use my de-windowed regular ASI120MM with the barlow. I was however able to compare both cams at prime focus, and found that with the AR window in place, required exposure times increased about 4-fold (!).
I had two cheap GSO barlows when I first started. A 1.5x 2" and a 3x 1"1/4. I was looking into Televues at the time and they were in the $300 a pop. I needed an assortment and thought too expensive. Then Peter Ward one day posted some deepsky shot he did on the keyhole in Ha with a Baader FFC and that blew my socks off. It was ~$800 at the time. I think it's in excess of $1k now. Still double the price of my telescope back then. But I thought that's likely the one and only barlow I'd ever need. x3 to x8 all in one. Some advanced planetary imagers swear by the Televues though.

Regarding chromatic aberrations I noticed also that my 462MC when debayered shows offset channels which is why I was getting fringing. Not necessarily the glass's fault so I'm looking into that too. I only noticed it yesterday playing with PIPP and splitting the OSC channels.

I haven't checked the window on my camera as well but because they're not cooled anyway can't hurt to try without. I've just received the ADC today in the mail so I'll have another go at Venus and Mercury as soon as those pesky clouds blow over.
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 04:38 AM.

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