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    SGL 2017 SP

alan4908

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About alan4908

  • Rank
    Proto Star

Contact Methods

  • Yahoo
    alanmarsh4908@yahoo.com

Profile Information

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

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2,890 profile views
  1. Fireworks Galaxy (NGC6946)

    Hi Wim I think you probably got that information from my response (above) - I image from an (almost) dark site which as you say, makes an significant difference to LRGB image quality. Alan
  2. Heart and Soul

    Excellent images - I particular like the shade of red and your processing style, which seems to give it an impressive 3D effect. Alan
  3. Fireworks Galaxy (NGC6946)

    Thanks Martin ! Alan
  4. Fireworks Galaxy (NGC6946)

    Martin Thanks for the comment. In terms of challenge, I actually found the star field, rather than the galaxy to be the most challenging aspect of this target - since I had blended quite a lot of Ha into my Lum for the galaxy - I found this gave a non optimal appearance for the starfield, so this consists of mainly an RGB starfield with only a small amount of blended Lum. Although my camera (SX Trius 814) can happily bin either 2 x 2 or 4 x 4, I've never tried it during DSO captures - mainly because I've always though I should image at the highest possible resolution, even in the colour space. The only time I tend to bin is when ACP automatically selects my bin mode when performing an autofocus or I'm creating a skymodel for my mount (which I generally do in twilight conditions to avoid eating into valuable imaging time). Anyway, I suppose I really should try it and compare the results to the unbinned version to see if my theory is actually correct (or not). Alan
  5. Fireworks Galaxy (NGC6946)

    Thanks for the comment Mike - yes, I'm happy with the detail, I've found that my imaging set up of 0.7 arc seconds/pixel seems excellent for my site. Although I image from an (almost) dark site, I also found that the addition of the Ha blended into the Lum really helped boost the image brightness. Alan
  6. Fireworks Galaxy (NGC6946)

    Thanks Olly - yes, I know what you mean about the star field - it took me a few processing attempts before I was happy with the result ! Neil, that is an interesting question - as far as I know it is simply the company's name, rather than the precision of any of the components. So, to me it is just marketing branding, presumably with the aim of conveying precision. However, I may be wrong Alan
  7. Fireworks Galaxy (NGC6946)

    Can I ask why you decided to go 'unguided'? My NEQ6 would certainly not manage that with 1800s exposures - not sure it would cope with 600s either. Thanks for the comment Adrian. My decision to go unguided was simply an attempt to improve my imaging efficiency due to the poor UK weather ! To explain: when I analysed my ACP logs when guiding with my NEQ6, I found that guiding was introducing several inefficiencies: the time waiting for the guider to acquire a guide star, the guider/mount settle time and losing the guide star due to intermittent cloud. With my NEQ6 imaging at 1.4 arc seconds/pixel I could only manage about 2 - 3 minutes unguided before the imaged stars resulted in unacceptable aspect ratios, so I realized this required a new mount. After a bit of research, I decided to go down the 10micron route, mainly because of the very positive user reports. That certainly explains it. But, what camera was used? (can't see the signatures from my phone) Thanks wim ! - strangely, dust always seems to be lurking in the background irrespective of your chosen imaging time. The image was taken with a SX Trius 814, giving me an imaging scale of 0.7 arc seconds/pixel. Alan
  8. For my first attempt at the Fireworks Galaxy, I decided to go for an LRGB image with an Ha blend in both the Red and Lum channels. Since the galaxy is not particularly bright, I found that the Ha blended into the Lum channel gave the image a significant signal boost. Despite the weather and lack of long nights, I somehow managed to capture just over 15 hours. I can only conclude that my recent move to unguided imaging is improving my capture efficiency.... Alan LIGHTS: L:11, R:9, G: 15, B: 9 x 600s; Ha:16 x 1800s. DARKS:30; BIAS:100; FLATS:40. Captured with an Esprit 150.
  9. IC1396 in Ha - WIP

    A 3nm Astrodon - which I've found is excellent at maximizing image contrast. It also helps at increasing imaging efficiency, to explain: since it's very narrowband, it's very good at rejecting light pollution. This allows me to image DSO objects that are quite close (in an angular sense) to the moon and still achieve a satisfactory result. I use this fact with my ACP controlled observatory which I've programmed to only acquire Ha images when the moon is up and a certain angular distance away from the moon. Since I can get quite close, I can acquire more images for a given quality threshold. Alan
  10. IC1396 in Ha - WIP

    Thanks for the comment Richard. Thanks - the image was taken with an SW Esprit 150 on a 10micron GM1000HPS, the camera was a SX-814. This combination gives an image scale of 0.7 arc seconds/pixel. Alan
  11. IC1396 in Ha - WIP

    Given that we have infrequent clear nights in the UK, I'm always interested in exploring ways of increasing my imaging efficiency. So, recently, I acquired 7 30mins Ha subs of IC1396 but I noticed that quite a few of the subs had eggy stars (see below - I think it may have been windy). Rather than discard some of these, I'd thought I'd explore if I could somehow use these in an image stack but in a way that wouldn't erode image quality. After a bit of research and considering that I had only 7 subframes including quite a few dubious ones, I decided to use the Poisson Reject algorithm in CCDstack. A feature of CCDstack is that you can see which pixels are marked for rejection within an individual sub frame. This is useful since it allows you to experiment with different rejection strengths and visually see what is going to be rejected. So, since I had about 5 eggy subframes and I was keen that my stars should end up round, I decided to set it to 5 iterations which means that it can reject up to the 5 pixels in each 7 pixel stack. After a bit of experimentation of seeing which pixels where being marked for rejection, I also decided to instruct the algorithm it to reject about 1% of all the pixels within each individual subframe. I've put the stacked result in quite a high resolution below. Alan
  12. Show us your one sub images!

    Hello In order to eliminate dust donuts in PS I use a technique from one of Adam Block's tutorial videos, it can also be used to remove scattered light issues. The video, which I would highly recommend, is here: http://www.adamblockphotos.com/store/p7/Dimensions_of_Photoshop_by_Adam_Block.html It's difficult to explain the technique in textual form, so I would really recommend buying the video, however, here's an attempt at an explanation - be warned this may sound complicated Your goal is to replace the defective area with a new background area that doesn't show any defects. 1. Open up the image in PS. 2. Make a copy of the image in the upper layer. 3. Make a selection around the problem area, the selection should be quite a bit larger than the defective area. 4. Move the mouse over the selected area and right click the mouse button - a menu will appear. Select Fill from the menu. Another menu will appear. In the contents box, choose context aware fill and click OK. 5. At this point your defect will have disappeared since it will have been replaced by a new background, unfortunately, this includes false stars etc which now have to be eliminated. 6. Select the spot healing brush and put it into context aware mode. Click on each of the false stars etc within the selection area until you just end up with just a background. 7. With the selection active, click on the mask icon. On the top layer you should end up with a black mask with the selected area in white. 8. Click back on the top image and go to select and reselect. The selection you made previously will reappear. 9. Turn the opacity slider down on the top layer to something like 50% - this will allow you to see the real stars etc in the selection area. 10. Select the mask and click on the paint brush icon with a hard brush and paint with black on the mask. Paint on the mask at all the points of the real stars. Basically, you are poking holes in the mask, so be careful where you poke since you don't want to let any of the defects through ! 11. Put the opacity slider back to 100% and you are done. Alan
  13. Deep Sky III

    Images taken with a Trius 814 and a Esprit 150
  14. M27 (Ha + L)

    From the album Deep Sky III

    This image consists mainly of Ha with a small amount of Lum also blended into the central region in order to to better resolve the stars. The corresponding LRGB image with an Ha blend in both the Red and Lum channels, can also be found in this album. It represents 5.5 hours integration time.
  15. M27

    Thanks for the comment Olly
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