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.

sgl_imaging_challenge_banner_lunar_close-ups_winners.thumb.jpg.b5fb18580607a749e382266fe55a02a1.jpg

NigeB

Advanced Members
  • Content count

    183
  • Joined

  • Last visited

Community Reputation

191 Excellent

About NigeB

Contact Methods

  • Website URL
    http://www2.le.ac.uk/departments/physics/people/nigelbannister

Profile Information

  • Gender
    Male
  • Location
    Rutland, UK
  1. NigeB

    Flaming Star and Tadpole Mosaic SHO

    That's a great image Sarge - I'd be 100% happy with it! Beautifully sharp and nice choice of colour palette. A1+!
  2. Looks fantastic! Thanks for the process information - very useful indeed. Nigel
  3. NigeB

    Thar She Blows

    Wim, thanks for this and your posts on my other thread - very useful! Nigel
  4. Hello Everyone, I've been at a meeting in London all day so am just catching up now. This has been a fantastic thread... thanks to everyone for their responses. MrsG, I was going to ask you where you learned your processing skills, and you've answered that. In the BC (before children) years my wife and I used to tour France in our Caterham - I reckon I was within about 20 miles of Olly's place on at least 5 occasions over the years. I may need to suggest to Herself that we attempt a revival and book a stay at Les Granges... Gorann, I really like what you did with the data - yes of course, please go ahead and use/post however you want (same for everyone else). I've added a note on my Astrobin entry that points back to this thread and credits the advice I've received from everyone here. I'm also getting the feeling that perhaps an image is never finished - there's always the temptation to go back and adjust processing. I know I'm going to be re-working the image (and revisiting some earlier targets) over the coming days. Nigel
  5. Hello Again, I've had an entertaining evening reprocessing the original files following the methods described in this thread. The difference is quite amazing. My version is not up to the standards of those posted here - my stars are rather "loud" at the moment and they seem to pop out of the image. I think I can see how to tone them down - I'll work on this a bit more. I don't have PS, so I'm trying to do as much as possible in PI - although I do have Gimp... I suspect I'm going to be working on this for several more days, but I feel like the image quality has already improved enormously thanks to your posts and is probably worth showing the delta here. So here are two versions from this evening. Many thanks again - this has been a real revelation. Nigel
  6. Hi Geordie85, MrsGnomus, Olly, Wow.... I'm astonished - your images are fantastic - thank you so much for your efforts. I have to say this is a revelation to me; I knew I was not getting the best out of the data, but I didn't expect to see such a big difference between my outputs and those of people who really know what they're doing! I guess I'm partly pleasantly surprised that the data I took was good enough to achieve these results; it's also sobering to see how far off my own processing approach is. I've just shown my wife, and she is similarly amazed. Thanks also for setting out your processes in detail - this is an enormous help, and I'm going to go back and work through this from scratch this evening following your methods. MrsG... Yes, that's a flat field problem in the L frame - I took twilight flats on the first evening, but not subsequently - big mistake, because this feature appeared in the later nights. Not at all! Thank you for your comments and efforts! Olly, am I right in thinking you're not a big fan of PI? Why is that? (I recall a post from you some years ago where you were talking about the usefulness of layers, which as far as I know, PI doesn't have). Thanks again; it's going to take me a while to go through the information in your posts and properly understand the logic, but I'll post an updated version of my own once I've done that. Much appreciated! Nigel
  7. NigeB

    Thar She Blows

    Hi Everyone, Many thanks for your positive comments / likes and constructive criticism! It is much appreciated. Richard - that's very helpful: I must admit that I'd not really noticed the green tint (I think I was so relieved to get rid of the red, that I was happy with anything else!) but yes, now you point it out, it's really obvious. I'll have a go with DBE and adjusting balance. But I also like your final suggestion to make the data available - that's a good idea. So I've uploaded the entire file set to my Dropbox area. There's a lot of it... I've started a separate thread under the Image Processing Techniques section, here: Wim - those are really useful suggestions which I'm going to try. Just so I understand correctly: you're suggesting an RGB combination at the beginning of the process; at what point should I add in the Luminance? Sorry: as you can see, I'm really at the bottom of this curve! Thanks again Nigel
  8. Hello All, Yesterday I posted the results of a recent imaging attempt on NGC4361 (The Whale Galaxy) over in the Imaging - Deep Sky section. Here's the original thread with a description of my method and what I'm not happy with: https://stargazerslounge.com/topic/313366-thar-she-blows/ In the post I asked for comments/criticism and some suggestions on how to get a better result. One of the suggestions (thanks @Allinthehead) was to make my data files available for others to work on - which sounds like a great idea. So I've posted the (~1.5 GB) of raw lights, flats, darks and bias frames on my DropBox area. I've also posted four fits files, which are corrected, aligned and stacked L, R, G, and B frames, in case anyone wants to have a go at processing but doesn't want to start from the very beginning. (Of course, these aligned and stacked frames may also contain errors from my processing method - so it's better to start with the raw files if you can!) So if anyone is looking for something to do when the nights are cloudy, I'd be really interested to see what others can do with this, because I'm well aware that my processing technique leaves much to be desired. I'm particularly keen to hear from people using Pixinsight, which is the system I decided to invest in. If you can make this look good, please post, preferably with a summary of your processing steps, so that I can better understand how to improve my technique. Here is the link to my Dropbox area containing the files - the zip files contain the raw data: https://www.dropbox.com/sh/th6595cdneqr24u/AADdUywsfzkARZ-917O_gHFta?dl=0 Thanks! Nigel (My own attempt shown below).
  9. NigeB

    Horsehead nebula in Narrowband

    Hi Sara, I think we need to invent some new superlatives. You've produced some amazing imagery - this is (in the very best sense) something else. And I like the colours. This region of the sky is a favourite target for many, and there are lots of good images of it out there - but this is like looking at the scene for the very first time. Amazing. Nigel
  10. NigeB

    Thar She Blows

    Hello All I tried to take full advantage of the three whole nights of clear sky we had last month in these parts - so three nights leaving the observatory open all night hoping it didn't rain while I was asleep... I decided to concentrate on NGC 4631, the Whale Galaxy which is well placed right now. Results below. All processing done in Pixinsight. I have to admit that while I'm quite pleased with the appearance of the image when seen from afar, I'm much less happy with the result up close. I've darkened the sky background more than I probably should, to try to conceal a multitude of sins. Image information: TOA-150 at f/7, Mesu 200 mount, Atik 460ex at -15°C, Baader LRGB filters, Lodestar autoguider via a TS OAG. L: 24 x 600 sec R: 14 x 600 sec G: 14 x 600 sec B: 15 x 600 sec Here are the main processing steps I applied: 1) Dark/Bias/Flatfield correction, alignment and stacking in Pixinsight using Winsorized sigma clipping. 2) Linear fit of R, G and B using L as the reference. 3) Applied a histogram stretch to all frames (transferring the Screen Transfer Function settings to make these permanent) 4) Performed Dynamic Background Extraction, subtracting the resulting background frames from images to remove some gradients and a few irritating flat field issues (some remain) 5) LRGB Combination performed 6) Increased saturation across the spectrum to bring out some colour. 7) Found that star sizes in the red image are larger than the blue and green. This was giving an excessive red tint to all stars. So I went back to the red frame, applied a star mask, followed by Morphological Transformation to reduce the red star sizes a little. 8) Re-did the LRGB combination + saturation increase. Found the red halo issue was helped, but not completely removed. 9) Applied a star mask and reduced saturation levels in the red channel for stars only. This removed the general red tint and brought out some colour in the stars. 10) Some adjustment of the R G and B curves and cutoffs in Histogram Transformation to try and get a colour balance in the galaxy which looked right (aesthetically). 11) Final tweak of overall RGB histogram to hide the worst of the background and achieve what looked like sensible brightness, contrast and colour balance. What I'm not happy with: the background is very noisy - lots of grain, lots of chromatic noise - zoom in and it looks terrible. Maybe a simple case of needing more data? The broader PSF in the red frame does not help - the star reduction process improved things a lot but I suspect is no substitute for a better match with L, G and B, and its effects are definitely still visible. It was caused either by a focus or a seeing issue (probably the latter). Lousy flat field - I relied on the first night's flats to correct the subsequent 2, and something had changed. Lesson learned. I could probably help to reduce the effects in post-processing but I think it's a second order issue compared to the other points above. Star shape is poor, possibly due to my heavily loaded mount (another thread on this elsewhere!) Comments, criticism and suggestions very welcome. Thanks Nigel
  11. NigeB

    M81 & M82 from Astro campsite

    Very nice! I think if those are bad gradients, then by amazing coincidence they seem to follow the contours of the IFN seen e.g. here... http://www.skiesbyafrica.com/Galaxies/M81-82.html
  12. NigeB

    LED lighting suggestions ??

    They can be cut at intervals along the strip - on mine there are cuttable joints every ~10 cm. Various lengths available.
  13. NigeB

    LED lighting suggestions ??

    Hi Skipper Billy, +1 for the LED strips. I've fitted these in my observatory. Note that these are the weatherproofed variety, which have a silicone-like coating that seals the LEDs and interconnects from water. This is important! A previous set I tried did not have the coating, and started to fail after a year or so: https://www.ebay.co.uk/itm/10M-SMD-5050-RGB-LED-Light-Strip-Multi-Color-Changing-TV-Back-Mood-Lighting-/251940925965?hash=item3aa8d9720d Don't rely on the adhesive backing to fix them - it'll almost certainly start to fall down after a short time. I used these clips: https://www.ebay.co.uk/itm/10X-50X-100X-LED-Strip-Light-Holder-Soft-Silicone-Fixing-Clip-for-Max-13mm-Width-/262487478722?var=&hash=item0 As Ray says, the dimmed red setting works well - I use it while setting up. On white, there's plenty of light for working on kit - shutting down, maintenance in the observatory etc. And as a bonus, you can select other funky colours for no good practical reason at all - I find a nice purple makes the kit look suitably WOW for visitors as they arrive in the observatory. Silly but fun. Here are some views of my installation. No other light sources being used so you get an idea of how bright the white setting is. Re: 12V. These come with a mains power supply, but the supply output is 12V. So (while I've not tried it) it should be possible to power directly from a 12V source. The specs indicate an output of up to 5A. Nigel
  14. Hi Fabiano, Good - powered hubs are less problematic. OK, seeing your other posts, it looks like you're en-route to a solution. Good luck! Nigel
  15. Hi Fabiano, The first place I'd look is your USB hub. If you search through SGL forums you'll find no shortage of posts from people with issues relating to hubs. Question: is it a powered hub (i.e., it plugs into the mains electrical supply as well as your computer's USB port), or is it unpowered (meaning it only plugs into the computer USB port)? Many problems arise from non-powered hubs. Nigel
×

Important Information

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