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Found 13 results

  1. Hi All, I am posting what I suspect is a newbie mistake question but hoping that someone can assist with the issue of flats. Although I have been fumbling around the sky, taking snaps at leisure, recently I became serious. I have read up about the different calibration files (flats, darks, bias) and they seemed to make sense; different ways to capture the image defects and extract those from the image of the sky. After a few weeks (months) of further fumbling I went back to the very first target to receive my attention, M42 Orion Nebula. In short, I took 20x 30s exposures in LRGB and ran these along with 20x LRGB each of darks, bias and flats. To obtain the flats I used a diffuse sheet of perspex (lightbox material) and an LED video lamp that has 180 white LEDs, turned to its lowest setting. Attached below is the stacked Luminance flat and the light image. In the lights I am getting very strong marks from dust and I had thought that the flats would subtract this but looking at the flats the marks are completely different shapes and do nothing to remove them from the lights. The attached has been further stretched to show the issue. Now, I am obviously doing something wrong but I have no idea what, any pointers from the vast pool of knowledge will be much appreciated. Thanks, Anthony
  2. Hi all, First post here, and I'm pretty new to AP, just picked up a Star Adventurer mount a couple months ago and have been happily playing around with it with DSLR and various lenses and a 72mm Sky-Watcher refractor. I'm new to the whole setup process, and I'm trying to do a decent job of leveling the tripod/mount, polar alignment, and I should probably think more about balancing the weight of things. I've gotten some decent shots, like 60-120 second subs with up to 300mm lens. My last time out I was getting star trails at 200mm and 15 second exposures, which could have been just a sloppy polar alignment, but today out of curiosity I looked through the polar scope and rotated the RA axis 360 degrees, and I saw that the target circle jumped a few times. I'm guessing that the target circle should appear not to move while the numbers 3, 6, 9, 12 would rotate around as I rotate the RA axis. So my guess is that the polar scope would need to be calibrated?
  3. When I look through my polarscope and rotate the RA arm, the cross hairs stay in the same place but the image itself moves. Is this a problem? I have tightened everything. Can you explain why the image moves? Is there another adjustment I need to do? Thank you, Gerard
  4. Hey all, finally got some guiding going last night, but at the bottom right of PHD2, the word "CAL" is yellow (as opposed to green) and says "Calibration: Completed, but scope pointing info not available/not in-use" Does this mean PHD2/SSAG isn't sending data to the mount, or the mount isn't accepting the pushes? It's an AVX mount, and my PHD2 graph isn't great, but RA and Dec stay within about 3" either way. But I can't tell if guiding is doing anything to the mount, or if my images are turning out ok simply because of decent polar alignment and just tracking. Any ideas what the above text means? - Josh
  5. Hi! Yesterday I was reading about dark frames vs in camera long exposure noise reduction, and something caught my attention. As far as my (so far little but growing) knowledge goes, the best you can do is to take the calibration frames right after the imaging session. This can be a pain in the A, and as I read yesterday, many takes these frames separately, when there is nothing better to do, like on a cloudy afternoon. This is allright, it's a good idea, you can create different master darks and other master calibration frames on different temperatures (room temp, cold, hot etc), and use these when stacking images from your light sessions according to the temperatures the lights frames were capured at. But. As far as I know, my darks should have the exact same settings and focus that my lights have. If I know I use for an example a prime wide angle lens at F2.8 all the time, with ISO 1600 to capture the milky way, that's okay. But what if something changes? What if I use ISO 3200 for some reason? What about the focus (okay, inifinity, but not exactly the same all the time when manual focusing)? What if I use a zoom lens on different focal lenghts? What about the other calibration frames? It's definitely not impossible to be prepared for every scenario, but when you use lenses instead of telescopes, there are more variations. Extra info, if that matters: I'm using a Nikon D5500, which is "ISO invariant". I'm really curious about your replies, as this could greatly improve my image's quality, if It's possible to take calibration frames this way. Thanks in advance! Árpád
  6. ( Edit 20 Aug: adjusted to increase brightness ) ... The Fighting Dragons of Ara ( NGC 6188 ) ( please click/tap on image to see larger and sharper ) ...................... Original: The Fighting Dragons of Ara ( NGC 6188 ) ( please click/tap on image to see larger and sharper ) Bright Nebula NGC 6188 and open cluster NGC 6193 are embedded 4,300 light years away in the Sagittarius arm of our Milky Way galaxy and can be seen with the naked eye south of Scorpius in the constellation of Ara. With powerful stellar winds and energetic ultra-violet radiation, massive stars sculpt the interstellar gas and dust of the nebula into wonderful shapes and cause the interstellar gas to brightly fluoresce. Closer to the hot young stars of the cluster, bright blue “sunlight” reflects off the clouds of gas and dust to produce the blue reflection nebulae seenin the image. Magnitude +5.19, RA 16h 41m 42s, Dec -48deg 48' 46". Approx. 3800 light years away. Image details: Plate Solution: Resolution .......0.586 arcsec/px ( original full size image ). Rotation .......... 89.764 deg. Pixel size ........ 3.90 um. Field of view ..... 58' 41.6" x 39' 9.5". Image center ...... RA: 16 40 09.856 Dec: -48 41 22.50. Image bounds:. top-left ....... RA: 16 42 10.059 Dec: -49 10 30.54. top-right ...... RA: 16 42 06.489 Dec: -48 11 57.14. bottom-left .... RA: 16 38 11.010 Dec: -49 10 39.74. bottom-right ... RA: 16 38 11.897 Dec: -48 12 05.58. Telescope: Orion Optics CT12 Newtonian ( mirror 300mm, fl 1200mm, f4 ). Corrector: ASA 2" Coma Corrector Quattro 1.175x. Effective Focal Length / Aperture : 1410mm f4.7. Mount: Skywatcher AZ Eq6 GT. Guiding: TSOAG9 Off-Axis-Guider, Starlight Xpress Lodestar X2, PHD2 . Camera: Nikon D5300 (unmodified) (sensor 23.5 x 15.6mm, 6016x4016 3.9um pixels). Location: Blue Mountains, Australia Moderate light pollution ( pale green zone on darksitefinder.com map ). Capture ( 24 June 2017 ). 12 sets of sub-images with exposure duration for each set doubling ( 1/8s to 240s ) all at ISO800. 34 x 240s + 10 each @ 1/8s to 120s. Processing ( Pixinsight - 19 Aug 2017 ). Calibration: master bias, master flat and no darks. Integration in 12 sets. HDR combination PhotometricColorCalibration.
  7. Hi everyone, I seem to have an issue with my NS camera that I can't figure out. Whenever I take a picture, every bright object in it, especially stars, have a black shadow on the right part of the image. I have disregarded the effect coming from the telescope or reflections from outside, because the shadow always appears on the right, regardless the angle of the camera with respect to the telescope. The effect is very apparent when I'm focusing. I have attached several pictures to see if someone can give me a hint: - ...004: focusing street lights - ...006 Calibration (Dark) - ...008 Calibration (Bias) - ...010 Calibration (Flat): pointing to a street light and trees - ...013 Focusing a star - ...019 Picture of street lights - ...003 Focusing a bright star - ...5420 Picture of a star field
  8. Hello. I have an unusual problem with my AZ-EQ6. I decided that I wanted to try pulse guiding rather than ST4, to get rid of a cable. I use MaxIm for all my controls, capture, guiding, pointing etc. and I use the EQMod ASCOM scope driver. My initial pulse guiding efforts worked ok, the mount would move and guide etc, no worries. I was not pleased with the pulse guiding results after some fluffing around so I moved back to ST4 and this seems to be where my issues started. Now, whether I choose ST4 or pulse guiding, my mount will no longer calibrate in the Y axis (Dec, I believe), or for that matter, guide. I have tried the move commands from inside MaxIm guide tab and X responds to a 10 pixel move but not Y. I tested with both PHD 1 & 2 with the same results. If it were a hardware issue, as in the mount has a Dec problem, would I be able unable to operate the mount with the hand controller or on screen motion buttons, both of which slew the mount fine? I could understand if the guide port were malfunctioning that ST4 would possibly have an issue but not when the mount slews as directed, so pulse guiding should work. Could it simply be that my EQMod driver has got confused and needs to be re-set, or am I looking down the barrel of sending my mount back to the dealer? Does any of this make sense? Thoughts and feedback most welcome.
  9. Re-processed 12th August 2017 using the new PhotometricColorCalibration tool from Pixinsight. This function seeks to adjust the colour balance of the image by plate solving the image and comparing the colour of the stars in the image with the colour values for these stars as stored in various databases. ( please click / tap on image to see larger / sharper ) ................. Trifid Nebula ( M20, NGC 6514 ) I manged to capture another 60 odd 240sec images in late July to add to the data I captured at the end of June ( Trifid Nebula WIP ) Trifid Nebula in Sagittarius ( Messier 20, NGC 6514 ) ( please click / tap on image to see larger and sharper )' and a crop of the main part of the nebula ... I am quite pleased with how the colour balance turned out - especially the colours of the stars ( my goal has been to get the colours of the stars as close as I can to how they would look with "daylight" whitebalance and no light pollution / sky glow). ----------- "High Dynamic Range" ( HDR ) image of the Trifid Nebula - built from exposures ranging from 1/8 to 240 seconds in duration. Image details: from nova.astrometry.net: Size: 52.2 x 35.5 arcmins. Centre: 18h 2 min 30.8 sec, -22deg 57' 37.7''. Orientation: up is -88.2 East of North ( ie. E^ N> ). Telescope: Orion Optics CT12 Newtonian ( mirror 300mm, fl 1200mm, f4 ). Corrector: ASA 2" Coma Corrector Quattro 1.175x. Effective Focal Length / Aperture : 1410mm f4.7. Mount: Skywatcher AZ Eq6 GT. Guiding: TSOAG9 Off-Axis-Guider, Starlight Xpress Lodestar X2, PHD2 . Camera: Nikon D5300 (unmodified) (sensor 23.5 x 15.6mm, 6016x4016 3.9um pixels). Location: Blue Mountains, Australia Moderate light pollution ( pale green zone on darksitefinder.com map ). Capture: 12 sets of sub-images with exposure duration for each set doubling ( 1/8s to 240s ) all at ISO800. Processing: Calibration: master bias, master flat and no darks. Integration in 12 sets. 105 x 240sec main image. 5 each for exposures 1/8 to 120sec - to caputure highlights. HDR combination using Pixinsight's PixelMath function.
  10. I'm new to planetary imaging and struggling with recording of calibration frames. How do I take calibration frames (bias, dark and flat-field) with a monochrome CCD (DMK) used with a filter wheel, do I have to record a video in AVI- / SER-file format or just a single image (in which format)? Wolfgang
  11. Hi I have the ZWO ASI120MC-S and I just can not seem to be able to calibrate it, tried everything I can think of, can not find much online. Any suggestions really appreciated as I'm randomly punching numbers hoping for results, I have a rough idea what the variables are going into but no luck. This is the best I can do sat here in bed with the bed light on.
  12. I'm a newbie in this hobby and last week end I had the opportunity to start testing my setup with guiding. I read a couple PHD2 tutorials and went on with it, I was successful taking 480sec exposures with round stars, so I pretty happy with my first attempt. My question is related with the Calibration data produced by PHD2, please check bellow my data: I'm not fully understanding the data.. 1) I assume a perfect tuned mount RA and DEC should align with the 90º graph scale. 1.a) Is this the orthogonality error ? 2) If my assumption is right, how do I correct the deviation ? 3) What are the white dots ? 4) Why the read and green lines do not align with the dots ? 5) What should I conclude concerning the performance of my mount by looking at the data ? I know.. a lot of questions.. Just a bit of context, my setup is a NEQ6 with an ED80 (0x85 reducer), for guiding I have a TSL80 (328mm) with an ASI120, btw the NEQ6 is fully stock. Thanks, -jb
  13. Hallo! I have written earlier about using dithering technic instead of traditional dark and bias calibration. I have updated my tutorial with a calculation of the noise from Dark/Bias vs Dithering calibration: http://astrofriend.eu/astronomy/tutorials/tutorial-dithering/tutorial-dithering.html#part06 Of course it's simplified but still show you what to expect, it depend very much on the camera and your site's darkness. This is a way to reduce the static pattern (column defects, hot pixel etc) in image. I hope you find it interesting! /Lars
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