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Mognet

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About Mognet

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    Star Forming

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  1. My first thought was comet 46P/Wirtanen as it's in the right area, but that's heading towards Pleiades. A geostationary satellite is more likely. As you have the exact date, time and location of the shots have you looked at one of the planetaria programs for the object?
  2. Mognet

    3D Printed Spool Holder (off topic)

    Those beat my slightly off the wall spool roller effort
  3. Mognet

    3D Printers

    Given the size of that print, I'm impressed. I've been considering the Ender 3 as a replacement for my rather basic iMakr Startt.
  4. Thanks Kat. I'll give it a try in DSS. My usual lens has some pincushion distortion that Sequator can cater for. I haven't seen if that's possible under DSS yet. Another thing I could try is to generate some TIFFs from the raw files using something that offers lens correction profiles and then run them through DSS
  5. And there was me thinking that frost on the scope was bad
  6. I've had a quick look at the Canon 1100D manual, which I'm guessing from your signature is what you are using. On page 94 it gives some information on how to adjust the aperture http://gdlp01.c-wss.com/gds/7/0300005057/06/EOS_1100D_Instruction_Manual_EN.pdf If your Yonguo lens is this one, then it looks like it is possible to control the f-stop that way, assuming they are compatable and the camera sees it properly. It's the same with my Nikon, manual focus via the lens ring and aperture control via the camera.
  7. While playing follow the link on Wikipedia after reading about the sad loss of early home computer pioneer Bill Godbout in the current California wildfire, I came across a reference to Gary Kildall, who along with being the creator of CP/M was co-host of the Computer Chronicles on US TV. Most of the episodes of which are now available on the Internet Archive. I've just watched one on astronomy software, which now looks very primitive compared to what we have available to us now, but was pioneering at the time https://archive.org/details/Astronom1986. The programme also has some very early digital imaging of Halley's Comet from the Lick Observatory. Also available is Computers in Space https://archive.org/details/space_2 from 1989
  8. I'm only just getting my boots on to go out for my session! Have been waiting for everyone to turn their lights off, and the streetlights too. Luckily I'm a night person anyway
  9. You should also be able to capture some of the larger brighter nebulae too. I've had the North American, California, Orion and Flame show up in mine using an unmodded camera, all using the same basic technique
  10. You are off to a good start there. Definitely Auriga, with M36, M37 and the starfish cluster are showing nicely.
  11. Welcome to the world of imaging frustration! I had the ISS photobomb my capture of Cygnus a couple of months ago. Other times it's been thin bands of clouds invisible to the naked eye. Only thing to do is take a deep breath and try again. Astrophotograhy is an exercise in patience and determination with our skies.
  12. I couldn't get my capture of Gemini to work as a normal stacked image, so I reprocessed using the motion trails option in Sequator. I think this is allowed under the rules, under the open to interpretations bit (@Grant as you set the challenge, can you verify that it's allowed?) Nikon D3100, Nikkor 1.8G 35mm prime, ISO1600, f2.5, 60 subs of 9 seconds. Taken 9th November 2018
  13. Noise from digital is a bit different to film. With film it was from the particles being much larger in the faster films. In digital photography it's from the mostly random electronic and thermal noise being amplified. The way around this with astrophotography is to take plenty of shots and stack them, averaging out the random noise to an even point leaving the signals hidden therein. I typically take 60 images using an intervalometer to control the camera. The Deep Sky Stacker website has a technical explanation, including the various ways to remove the non-random noise. For now just concentrate on taking the light frames (the star images) and once you've got the hang of that, the flat images. In Sequator, click on Composition, and click on the 'Select best pixels' radio button. This changes the calculation from average to sigma clipping. It will take care of all but the worst satellite and plane trails. For the worst trails the only thing is to exclude the photo from the stack or delete it entirely. Another way is to take the images later at night as the sky tends to go quieter after 11pm here. My typical setup in Sequator is: Composition: Align stars. Normally I leave the calculation as average, unless satellite trails show up Sky region: Full area (default) Auto brightness: On. Sometimes turning this on improves the stack, sometimes it doesn't High dynamic range: Off (default) Remove dynamic noises: Off (default) Reduce distotion effects: On, and set to complex. DSLR lenses can cause a pincushion distortion effect. In normal photography it's not that noticable and processing software can take care of it. But when when stacking raw images straight from the camera, the rotation from image to image makes a mess of things towards the edges Reduce light pollution: Off for the trial stack, and then on with the uneven setting depending on the results from that. The amount of reduction can be adjusted too Enhance star light: Off (default) Merge 4 pixels: Off (default) Time lapse: Off (default) Colour space: sRGB (default) Light pollution will cause a gradient across the background of the stacked image, and it gets more noticeable when the image is stretched. What I generally do is to take the stacked image into GIMP, select Colour->Levels from the menu and then click on auto input levels. I call this the 'nasty process'. It's no good for processing images, but it will show up problems like gradients and satellite trails. It's then that I go back and re-stack using the reduce light pollution option until the problem is minimised, and then I can process properly.
  14. The lightness of the background might be having images that are too bright to start with. There is some advice on page 1 of this thread about using the histogram to check initial exposure settings. It could also be from the stacking software settings, depending on what you are using Sharp focus takes a bit of practice and patience. I generally start using autofocus on a distant bright light, and then switch to manual focus on the stars. From there I make gradual adjustments to the focus, checking the image after capture using the image zoom for sharpness of stars in the centre and corners, until they are as sharp as possible. I do the focussing part with the lens at f1.8, but for capture I usually stop the aperture down to f2.5. This sounds a little odd when supposedly trying to catch as much light as possible, but it helps to get sharper star shapes, control vignetting, and remove some of the lens distortion. ISO1600 and 10 second exposures should be fine at f2.2 or f2.5
  15. Another from the early hours of 9th November, and before the streetlights went out. Fortunately Auriga was reasonably high and in the least light polluted part of my sky which means I only needed to crop and make one slight adjustment in GIMP to darken the background and remove most of the camera noise Nikon D3100, Nikkor 35mm prime, ISO 1600, f2.5. 60 subs of 9 seconds each stacked in Sequator
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