Jump to content


Whirlpool Galaxy M51 - modded DSLR

Recommended Posts

my first DSO pic in aaaages, since October last year in fact, large doses of real life have been getting in the way.  A very common target, but my best take of it by a long way:


18x 420s lights at ISO1600, bias darks and flats, 1.5x barlow, equipment as per sig, developed in Pixinsight.


And just for a laugh, here is my previous effort:


  • Like 19
Link to post
Share on other sites

a massive improvement. Great job!

Maybe my screen is not calibrated right, but you're background seems very very dark, maybe you clipped the blacks a little high? But absolutely nothing else to moan about, beautiful picture :)

Kind regards, Graem

  • Like 1
Link to post
Share on other sites
13 hours ago, graemlourens said:

a massive improvement. Great job!

Maybe my screen is not calibrated right, but you're background seems very very dark, maybe you clipped the blacks a little high? But absolutely nothing else to moan about, beautiful picture :)

Kind regards, Graem

Hi Graem,

I think i am perhaps a victim of screen calibrations - it's definitely not clipped, I'm very careful about that, but on the laptop I use to process it's actually still a little light for my tastes, about right on the home desktop (even though both are supposedly gamma calibrated) and a little dark on this screen at work.

Maybe I should just aim for a given numerical background level.  Do other people think the background is too dark too ?




Link to post
Share on other sites

Hi Stuart.

I know exactly what you mean, i always go too dark if i use my old monitor at home.

Now i got used to just knowing the 16 bit value (for me i go for 6000-7000) and in photoshop in RGB mode i have heard most people target 20-30 (8 bit)
But i guess this is like most things in AP, everybody can do it as like like, and in the end you must like it :)

I have seen though, if you go too dark, and then you print it, printing in most cases will make it even darker, so lots of detail gets lost.

Kind regards, Graem

Link to post
Share on other sites
3 minutes ago, graemlourens said:

16 bit value (for me i go for 6000-7000) and in photoshop in RGB mode i have heard most people target 20-30 (8 bit)

hmm, so a % value of about 10% - I'm definitely lower than that, to be honest I usually target about 3.5%.

I'll have another little play with it this evening (fortunately that stretch was the very last step !), see how it looks with a lighter background

Link to post
Share on other sites


Celestron Omni XLT150 newt (150mm ap, 750mm fl, f/5) +coma corrector, AZ-EQ6GT, QHY5L11C+ T70 guiding, modded Canon 1100d

I used the Canon 1100d through a 1.5x barlow (I know you're not supposed to, but I think i got away with it)

Link to post
Share on other sites

how does this one look ?  Background is a bit lighter now, about 8%, any more looks a little washed out to me, though that could be the gamma on this screen still (which I've just re-done)



3 minutes ago, giorgio_ne said:

Great, great image! Are you located on a dark site in Spain, as per your signature, or in London as per your profile settings? Just curious...

Hi Giorgio, thanks very much !  I live in London, (Dulwich, not far from you !) but to be honest I don't bother doing any astro here due to our light pollution.  We've got a small place in Spain in the middle of nowhere though, so when down there I do enjoy some lovely skies.

  • Like 6
Link to post
Share on other sites

Oh i love that version so much more!

To me at the beginning also the goal was to keep background as dark as possible, but as the sky is not dark at all (indeed it is very bright!) my opinion is that this represents (to the eye) more the actual sky (but i must admit, that i gradually adapted this opinion from experienced astrophotographers around the globe)

Kind regards, Graem

  • Like 1
Link to post
Share on other sites

thanks !

There is some noise reduction, yes, though the camera is not too noisy.  I find  MLT Transform n/r and then TGV denoise is a good combination in Pixinsight, but I deliberately dialed it back several steps from where the noise is 'removed', and let some of the noise survive, I think it helps it to look more realistic and in-focus if there's a touch left in there.  If you zoom in on the tidal tail bits for example, you'll see some.  I was more brutal in removing chrominance noise though.

  • Like 2
Link to post
Share on other sites

Hi Glowingturnip,

I was just scrolling through this post. Liked your improvement a lot! But my first thought was that the background was very dark and that you should be able to get some of the wisps I've seen in other posts with this kind of quality data. Further down I noticed that I'm not the first with this thought and finally reached your new processing attempt. And NOW you are spot-on. Would love to have a go at this target but, alas, I live on the wrong side of the world...

Nice going :)



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 jacko61
      After some trial and error I'm getting some very good guiding results with PHD2 now. 60mm guidescope and ASI290MM mini camera. The M42 image taken late March was 12 x 15 second exposures taken manually with my dslr / C8 and a stopwatch. Stacked in DSS and played with a bit in GIMP. On the night I couldn't get APT to register the camera - turned out to be the mini USB cable (although later trials point to the socket in the camera being a bit loose too). 
      Bought an iOPTRON iPOLAR that arrived on Friday and had a play with that which has resulted in near perfect polar alignment. 2 star alignment and an additional 2 calibration stars on my Advanced GT mount means I'm getting very accurate GOTOs now and PHD2 (through the ST4 port on the ASI camera) seems to be guiding very well.  Last night after more cable faffing I managed to get everything working together to the point where I felt confident enough to leave it running by itself for an hour and a half (45 minutes of 180 second exposures plus 3 minutes each exposure to save the file - I've since found out I shouldn't have noise reduction switched on in the camera - DOH!) so M51 is 15 x 180 second @ ISO 800 lights and 5 x 180 second darks.  A little manipulation in GIMP and I think it's come out very well. Obviously still have a lot to learn and I'm going to have to start taking much longer exposures  but I'm quite pleased with these 2 pictures. 


    • By dazza1639
      2020 hasn’t been a great year for anyone, but we’ve had a good comet, and some clear nights. I haven’t been the most productive, or even a very good imager this year, but I’m quite pleased with what I’ve learnt, narrowband has been a revelation . So I thought I would share a few of my images, and a video I put together or them. Thanks for all the great images and tips that have been posted. Wishing you all a happy Christmas and a great 2021.

    • By chriscoles
      Hi, I have taken mono LRGB images of M51 with my new ASI1600mm-PRO.
      I have a mix of 30s, 60s, 120s subs. 100 darks, and 100 flats for each filter. About 4 hours total.
      I Used DSS for alignment and stacking, then Pixinsight for LRGB combination.
      My issue is that i'm not happy with the colours, the stars all appear white and the background is strange.
      I have attached the Aligned LRGB images.
      Can anyone point me in the right direction? Thanks!

      Green.TIF red.TIF Lum.TIF B.TIF
    • By EyeGuy
      This is from a couple of nights ago.
      It clouded in quickly, so I didn't get much data. The temp was 2C, and I'm self-isolating - so that was also a factor! I only took 5 darks before I gave up and went to bed. I'll take more when the temp is right.
      This is 140 min integration time on a new Canon EOS Ra with 17x500s exposures, and no filter (from the city).
      Processed in PI and Photoshop - I should have used more star masks but the data aren't good enough to warrant the effort I think. I also had difficulty with flats - I tried a range of exposures with a Gerd Neumann panel, but I think they were all too short. Will go longer than 0.3s next time - very hard to figure out flat exposure on DSLRs, and APT's tool doesn't work for DSLRs yet.
      I think I'm obsessed with M51 - and I know I'll be back to it again.
      Stay safe everyone,

    • By knobby
      First attempt at any DSO other than the brighter stuff like M42 or Andromeda.
      Learning to use the AZ-Gti /Sharpcap polar align / windows synscan app / APT platesolving ... And guiding ! all in one night ?
      all went well so had a quick 30 mins on M51 (first time I'd ever managed to actually frame it ... Plate solving is amazing)
      90 second subs gain 420 and 5 darks and synthetic flat for dust bunnies / gradients
      Wish I'd have gone longer now as tried a 5 minute sub once guiding was working which looked good .
      Very noisy but only 30 mins .

  • 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.