Jump to content

sgl_imaging_challenge_2021_annual.thumb.jpg.3fc34f695a81b16210333189a3162ac7.jpg

Recommended Posts

Firstly Happy New Year everyone!

Afraid I'm far from a frequent poster here on the forums, my last deep sky image through a scope was a DSLR image back in March 2012 ... around the time I stopped using film ... better late than never.  :smiley:   

Since then I have just made the move from DSLR to CCD during Spring 2015 and thought I would share my first finished effort, image files have been in my computer since September  ...just a fun experiment to see what could be resolved along with image scale, the image scale is 100% but cropped very slightly due to stack overlap so about 95% of total sensor area.

Colour wise this is my first LRGB aiming for rustic/teal which I feel is more natural ...rather than red/blue, also trying to retain subtle detail as best I can at this FL. and limited number of subs, thanks for looking, details below.

APM 175mm Refractor (barlow to FL 3780mm)
Atik 414EX (mono) at -20'C / Bin 1x1
EFW-2 Astrodon E-Series LRGB filters
Multiple exposure between 15s & 300secs
Sequence Generator Pro
Deep Sky Stacker
Pixinsight
CS6 Extended

24004966542_c75106d34c_o.jpgM57 Ring Nebula NGC6720 by Mike Dickson, on Flickr

  • Like 16
Link to post
Share on other sites

Gosh, that's quite something. 

We don't see many Rings because of its small size. Brave of you to Barlow it, though! (This would be a good image for discussing the F ratio myth because, though you slowed your scope down to what, F16, the number of object photons remains unaltered. We don't see many DS images at F16 for that matter, but there you go!)

I'm certainly impressed. What did you gain from the short subs and might you have been temped to try longer?

Olly

Link to post
Share on other sites

Hi guys

Thanks for your positive comments... appreciated! :-)

Olly if the calculation FL3780 divided by aperture still holds true when a barlow is used in the imaging train then this should be f21.6 ...but if any optical experts know better please correct me.

I could quite happily have continued with longer exposures but the limiting factor was the seeing conditions at this FL, in some images stars were eggs and others smeared as you might expect but enough passed to produce this result.

The other factor was simply that longer exposures than 360s were bordering on burning out detail while very short subs were too noisy.... many more short subs would have been required.

Also

I knocked a cup of tea over my imaging laptop today... puff of smoke from the fan outlet, intermitent fan running but display dead... thankfully it was just a cheap Celeron from the supermarket.

Mike

Link to post
Share on other sites

Sorry about the computer!

I'm very surprized you should say that you were over exposing at this kind of F ratio in 5 minute subs. I never worry about exceeding 65000 counts on the capture screen because this will usually just be the stellar cores and I regard them as either expendable or replaceable either from short subs or, if the long subs are in luminance, by not applying them to the RGB-only stars.

However, this is a very delicate result.

I think I might buy one of those children's spill-proof beakers for my office tea...

:grin: lly

Link to post
Share on other sites

"Hi Mike,Wonderful image,now if it had been a drop of whiskey :grin: it might of evaporated before it ruined your pc, look forward to seeing you at Galloway later in the year".

Thanks Mike

I think flames from the fan outlet instead of smoke! ;-)

Unlikely to make Kielder/Galloway this year but things should be back to normal for 2017 ....will be great to meet everyone again. :-)

"Lovely image - Happy New Year!"

P

Thank you, you too. ;-)

"Sorry about the computer!

I'm very surprized you should say that you were over exposing at this kind of F ratio in 5 minute subs. I never worry about exceeding 65000 counts on the capture screen because this will usually just be the stellar cores and I regard them as either expendable or replaceable either from short subs or, if the long subs are in luminance, by not applying them to the RGB-only stars.

However, this is a very delicate result.

I think I might buy one of those children's spill-proof beakers for my office tea..."

:grin: lly

Olly, thanks for your input, yes I was surprised too to see overexposure in such short subs, that lower edge of the ring is one of these M42 or M31 type targets that requires a mixed sub lengths. I also tested on the Fetus Neb and clearly would need above 300s subs so depends on subject.

Adding the RGB helped neutralize the overexposure.... perhaps not so much burning out in the true sense so much as detail was being lost and becoming very bland.

Well guess this is what happens when you play with your toys at the kitchen table. :-/

Best wishes everone!

Mike

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    No registered users viewing this page.

  • Similar Content

    • By SuburbanMak
      Was about to turn in tonight when I noticed it had finally cleared so I headed out into the garden planless for a quick look around with my recent eBay Hilkin 60mm f13.3. 
       
      Seeing was actually pretty steady & transparency up high improving all the time. 
       
      I’m still waiting on the Vixen converter which will allow 1.25 eyepieces so took out the array of .965s which are in varying stages of disrepair. 
       
      There is something satisfying about the way they slot into the split-cut diagonal with no thumbscrews - shame most of the higher powers seemed borderline unusable. 
       
      The 25mm though gives a nice crisp view and I congratulated myself on my bargain looking at some lovely tight concentric rings either side of focus on Vega before hopping up to Epsilon Lyrae. 
       
      Stepping down the focal lengths I was just about splitting the more southerly pair with a 12.5 mm (64x) and not a bad view. The 9mm (89x) on axis confirmed this lower pair & showed some elongation in the fainter, more northerly pair. Kind of dim view though.
      The 6mm & 5mm were hopeless. 
       
      Popped the 25mm back in and took a pot shot at M57 which to my delight showed as a tiny but crisp circle.  Tried to step up the magnification but it was not happening. 
       
      Enjoyed a nice contrasty view of Alberio for a while - really do like the tight pinpoint stars, good colour and inky background in this scope. 
      It’s a lovely still, warm night but the town clock striking two reminded me I have work in the morning so I took one last sweep around the rich centre of Cygnus.
      I landed on a pretty little cluster a bit like a micro-Pleiades & realised I was looking at M29 - a thrill to have tracked down a new-to-me Messier object with this lovely old instrument. 
      I’ve hatched a plan to see how many of the lunar 100 I can observe with the Hilkin - seems a fitting task for it!

      As I packed up a huge Skytrain of 20+ satellites went N-S behind Deneb - biggest one I’ve seen and amazing in its way. 
      Lovely all-analogue couple of hours well spent. 
       
       
       
    • By Quetzalcoatl72
      Below are consecutive raw pictures if the ring nebula I took with my canon 600da and RCT 8" with neq6 pro guided with sharpcaps polar alignment procedure on the 15th of this month at 1am. I have 20 of these all 1600 iso auto wb 2 minute exposures. The problem will become apparent when you closely examine them, tracking is almost completely broken. I only stacked about 8 of them as most of the frames are unusable, some are star trails, some are commas and some are double exposures. This has become standard and getting worse since I tampered with my mounts gears and backlash adjustment. I have never been able to get consecutive 3min exposures on this mount, and I got it new 6 years ago, and only used it less than 30 times. I have spent roughly 20 hours trying to get rid of the backlash, coffee grinding noise and knocking when I press the directional keys to no avail, when the keys are pressed I notice the image wobbles violently. The go-to is also not working to 100% efficiently, I have to do guess work if I want my image centred.
       










    • By stevewanstall
      Messier 57 is is just coming into a position for a decent look around 11 30 pm. IT is a colourful object and I thought it would give me a good target with which to practice my colour developing in PS/Lightroom. I have read so much about how to produce a LRGB image from the four stacked/calibrated luminance, red, blue and green images,  a lot seems contradicatory and some, when followed, gave me colour yes, but not as we know it. I am sure a fair chunk must be put down to me. Anyway, I now have a work flow which gives me colour, sometimes resembling what other people have obtained. Progess of sorts.
      This images is based on 114s subs at gain 139, offset 21.
      L 39, R 20, G 20, B 19
      Calibrated  and stacked in DSS (flats, dark flats and darks)
      Messier 57 Ring Nebula in Lyra
       

      NASA: M57, or the Ring Nebula, is a planetary nebula, the glowing remains of a sun-like star. The tiny white dot in the centre of the nebula is the star’s hot core, called a white dwarf. M57 is about 2,000 light-years away in the constellation Lyra, and is best observed during August. Discovered by the French astronomer Antoine Darquier de Pellepoix in 1779, the Ring Nebula has an apparent magnitude of 8.8 and can be spotted with moderately sized telescopes.
      Equipment: Celestron 9.25 XLT at F10,  Skywatcher EQ6 Pro GEM, ZWO 1600MM Pro, ZWO EFW with ZWO LRGB filters, QHY5IIC guide camera on Skywatcher 9 x 50 finderscope, Celestron Focus Motor
      Software: Ascom 6, Eqmod, Cartes du Ciel, AstroPhotography Tool, PHD2
       
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.