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alan4908 last won the day on September 9

alan4908 had the most liked content!

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About alan4908

  • Rank
    Sub Dwarf

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  • Gender
  • Interests
    Astrophotography ! ....at the moment I'm concentrating on deep space imaging
  • Location
    East Sussex

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  1. alan4908

    Deep Sky III

    Images taken with a Trius 814 and a Esprit 150
  2. alan4908


    Hmmmmmm.....however, just for you Stuart: here is the result of the image which results from the stacking of the three 600s red sub frames which contain the supernova. Unprocessed, apart from the stretch and the arrow !
  3. I use the following software for processing my images - you can see the results by going to my gallery. I seem to have collected quite a lot of software over the years.... 1. Pixinsight - now my main processing source. 2. Photoshop - now mainly used for cosmetic corrections and colourisation. This used to be my main processing source along with CCDstack. 3. CCDstack - I still use this for calibration and sometimes permanently stretching images since it is so easy to use. One day I shall move to using PI for calibrating my images. 4. Registar - I use this for registering images that other programs cannot. It is very useful for moasic construction. I also find that it is sometimes useful to re-register RGB mages in this program if you are having problems with star colours. 5. Gradient Exterminator - a plugin for Photoshop that eliminates gradients. I sometimes use this but now find it is largely replaced by PI's DBE. 6. Noels Actions - a plugin for Photoshop that has a variety of excellent actions, some of which I still use (eg increase star colour). 7. Straton - a stand alone program for removing stars in images. 8. NeatImage - a stand alone program to reduce noise in your images. This is very good but I find that I'm using this less as I gradually get more proficient with PI's TGV Denoise. Alan
  4. alan4908


    Thanks ! - yes, it was taken with my trusty SX Trius 814 - which gives me an imaging resolution of 0.7 arc seconds per pixel. I was a little concerned when I first used it with my Esprit 150 since I thought the imaging resolution might be too small, however, it turned out that for my set up/site that it appears about optimal. Alan
  5. alan4908


    Thanks Alan. On the Esprit 150 - Yes, I'm very happy with the scope, it is excellent quality for the price. On the SN - unfortunately, the SN only appears in three of my Red sub frames so, attempting to force their inclusion isn't going to work - I'd just end up with a red SN . Personally, I doesn't bother me since a SN just appears as another star, albeit in an unexpected position. Thanks Martin - yes, my site (aka back garden) in East Sussex is quite dark (no street lights), it is also relatively high which seems to help with good seeing. The only downside is that it does get quite windy, although my roll-off roof observatory protects most of the scope from the gusts.
  6. alan4908


    M100 is located in the Virgo cluster at a distance of 55million light years, it is one of the brightest and closest galaxies within the cluster. It's a spiral galaxy with a pronounced bar at its centre. Quite a few supernovas have been found here, the most recent being in 2019, designated SN 2019ehk which was discovered on 29th April. The LRGB image below represents 12.3 hours integration time and was taken with my Esprit 150 (For those that might be interested: the data was gathered between Feb and May 19 , so I was wondering why I couldn't see the supernova in the image. On examination of the individual subframes it transpired that I captured it in only a handful of subframes, it's first appearance was on the night of 29th April. So, when I stacked the image, the supernova was simply rejected as a statistical error..... I think I've come to the conclusion that I'm not cut out for supernova hunting ). Alan LIGHTS:: L:26, R:19, G:13, B:16 x 600s, DARKS:30, FLATS:40, BIAS:100 all at -20C.
  7. Thanks Knobby Thank you Alan.
  8. Thanks Peter. Hi Rodd Yes, Narrow Band imaging is great for revealing detail but in my opinion you cannot beat LRGB from naturalness. I do agree it is difficult, particularly when you have nebulosity around. Yes, it is a crop, although not very much has been chopped ! Alan
  9. SH2-201 is a small emission nebula located in Cassiopeia. It is often captured as a by product of the commonly imaged Soul Nebula (SH2-199), which is partially shown here to left of the SH2-201. On the annotated image below, I've also marked the location of a Herbig-Haro object (HH-163). These transient objects are formed when high speed narrow jets of partially ionized gas from new born stars collide with nearby clouds of gas and dust. Typically, they only last a few tens of thousand of years. On the processing front, I decided to process the nebula separately from the starfield by firstly removing the stars and then adding them back, which seemed to help in getting better definition of the blue stars within the nebula. This LRGB image has a Ha blend into the Lum and Red channels and represents about 31 hours integration time. It was taken with my Esprit 150. Alan LIGHTS: L:40, R:19,G:22, B:17 x 600s. H: 30 x 1800s. DARKS: 30, BIAS:100, FLATS:40 all at -20C
  10. It is not necessary to purchase CCDstack (although it is a very good program). When processing in Photoshop, Adam primarily uses CCDstack for a Digital Development Processing (DDP) stretch of the luminescence image such that the object of interest will end up with a lum level that is around 180 (ish) - if you end up with lum values more that 200 then it will be very difficult to colour. So if you don't have CCDstack, then all you need to do is find a program that can perform a DDP or similar stretch on the lum data. Alan
  11. Hi Ole Many thanks for your comment. You raise a very interesting point regarding the background level. To me, there are two complementary approaches to the processing of deep sky objects: 1) Stretch the background and the main object of interest at the same level. The main advantage of this approach is that it highlights details everywhere. The main disadvantage is that you can end up with bloated stars, white star cores and white clipped objects which can distract from the object of interest. This distraction effect will increase the more that the image is cropped since the background details will get proportionally larger. 2) Process the background separately from the object of interest. This has the advantage that you can control the relative emphasis level of the object of interest, star bloat can be better controlled and white star cores along with white clipped objects can be avoided. This also allows you to significantly crop images to emphasize the central object of interest without enlarging distracting background detail. The main disadvantage is that you loose background level details. I use both approaches, selecting the approach that is appropriate to what I'm trying to achieve. In the above image, I choose approach 2) and ended up with a background level of about 18 (0= black, 255 = white). This was primarily because I wanted to dim the stars and background to a level that I judged emphasized the object of interest (eg NGC7331) to best effect. However, if this was a much wider field of view, say NGC7331 including Stephan's quintet, then I would have used approach 1). To me, this is all very much personal taste with no right or wrong answers. Alan
  12. Although the book "The Deep Sky Imaging Primer by C Bracken" is called a primer I would regard it as an intermediate level book. It's contents are about 50% about processing images. Personally, if you want to learn on how to improve your Astrophotography Photoshop skills I'd first go to the Adam Block video tutorials. Alan
  13. Some excellent books on (Photoshop dominated) processing of Astronomical images would be: 1 - Photoshop Astronomy by R Scott Ireland - incredibly detailed but maybe slightly dated. 2. - The Deep Sky Imaging Primer by C Bracken - also covers acquisition. 3. Lessons from the Masters - Edited by R Gendler - Advanced. Whilst the above books are very good, I would also suggest that you consider some world class video tutorials from Adam Block - see https://adamblockstudios.com/categories/DimensionsOfPhotoshop Alan
  14. Hi Rodd Yes - the image is definitely cropped ! - I normally crop away until I get the prettiest picture. FYI the camera I'm using is the SX Trius 814. Alan
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