Jump to content

Stargazers Lounge Uses Cookies

Like most websites, SGL uses cookies in order to deliver a secure, personalised service, to provide social media functions and to analyse our traffic. Continued use of SGL indicates your acceptance of our cookie policy.

stargazine_ep28_banner.thumb.jpg.b94278254f44dd38f3f7ee896fe45525.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

Share this post


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

Share this post


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

Share this post


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. 

Regards and a happy new year.

Mike

Share this post


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

Share this post


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

Share this post


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 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
       
    • By lenscap
      Skysafari lists Delta2 Lyrae as a double, with magnitudes  4.28 & 11.20,      But search stelledoppie.it
      and this is a summary of the result; a multiple with 11 components potentially visible in an amateur scope.

      This is my plot of the above data.

      With a 200p F/5 in Bortle 8 skies/ average seeing, I have seen the 6 brightest components to mag 10.30. The mag 11.20 should be doable but has eluded me so far.
      I think that for my setup, the dimmest 4 stars will need darker skies or better eyes 😀
      If you are observing Delta2 Lyrae, how many components can you identify?
    • By alan4908
      My first attempt at M57.  I attempted to capture the extended halo by gathering some OIII and Ha data and then blending these into Blue and Red channels, respectively of an LRGB image.  The image below represents about 21 hours and was taken with my Esprit 150.
      Alan

      LIGHTS: L:13, R:13,G:8. B: 10 x 600s; Ha:13, OIII:14 x 1800s. DARKS:30, BIAS:100, FLATS:40 all at -20C.
×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.