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Roy@Aldermaston

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Everything posted by Roy@Aldermaston

  1. I've just put together a polar scope webcam using a Logitech C160 as the Phillips SPC900NC is no longer available at a sensible price. Last night I tried it out for the first time and was disappointed to discover that although the reticule markings were clearly focused, there was no sign of Polaris. I played with the various settings in SharpCap, but couldn't find Polaris, which was bright and clearly visible by eye through the polar scope. I didn't have the SW Synscan handset connected and the reticule was quite brightly illuminated, which may have been part of the problem, but the clouds rolled in before I had chance to check it out. I would be grateful if anyone could suggest a solution - is the camera not up to the job, or is there something obvious that I'm missing? Thanks, Roy
  2. Peter, Once you have the connect equipment panel open in PHD2, select the small button, with a crossed screwdriver and spanner icon, next to the camera name. That will open a dialogue which allows access to the gain slider . I have mine set to 98%, which at my location works well with 2 sec looping. Roy
  3. Thanks Steve, The spacing was set up by Bern at Modern Astronomy and checks out OK, and apart from cropping to remove the over-scan the image hasn't been processed. I never had that banding before, but its appearance does correspond with with the adjustment of gain and offset to higher values. Once the weather clears I'll experiment with the new settings before tackling the curvature issue. Roy
  4. Thanks Simon, I've had another go and worked through the sets given in the manual. The values that I've come up with are Gain = 3 and Offset = 120, and that seems to agree with those that others are using. Now all I need is a clear sky and no wind. Roy
  5. Thanks Steve, I'm relieved that it's probably me and not the camera. When setting the gain and offset should I have my LP filter and MPCC fitted as usual, and does the camera need to be fitted to the scope, or just free standing. Roy
  6. Thanks for the replies. I've attached a zipped stack of 11 600 sec lights taken with gain at 15 and offset at 125. There is a strange circular banding effect around the image centre when its stretched, perhaps caused by having the gain set too high, its certainly produced spectacular vignetting. Roy NGC7142.zip
  7. I would welcome advice from anyone who has experience of the QHY8 Pro camera. I bought it as a step up from my modded Canon 1100D, but aside from the advantage of step-point cooling it's proving to be an expensive disappointment. Compared to the Canon, the images lack contrast and overall it seems far less sensitive. I've spent hours of wasted imaging time trying to get the right balance between gain and offset, using both the manufacturer's instructions and the many contradictory methods posted online. None seem to produce any significant improvement. I'm beginning to despair of ever getting reasonable results, so if there is anyone who uses this camera and is satisfied with the images that it produces I'd be more than grateful to hear from them, and would welcome any tips for setting the gain and offset. Excuse the rant, Roy
  8. I've mostly used artificial flats with the subs from my 1100D, but its about time that I got to grips with the real thing. So far my efforts have worked well at removing dust bunnies, but have been less successful with vignetting. The problems is this: by lights show the usual pattern of vignetting, being bright at the centre of the frame and fading in a circular fashion towards the edges. Not so with the flats: the centre of the vignetting is displace towards the bottom of the frame, such that when stacked the final image shows a horizontal gradient along the top of the picture. I've tried the "tee shirt" method and using a laptop screen to provide illumination, but either way I end up with the same problem - any ideas. I've attached a stretched flat to show the effect. Thanks, Roy
  9. I've used it for a trial period and it does work, although it sometimes produces odd colour casts. However, I found it to be less affective than Fitswork, a freeware program with other useful flatten and noise reduction functions. If you want to try Fitswork 4 here's the link: www.fitswork.de/software/softw_en.php
  10. Poor seeing of late with very misty conditions, hence this is a rather noisy image. 15 X 420 sec lights @ ISO 800 and 5 darks. Taken with a self modified 1100D Thanks for looking, Roy
  11. Congratulations Paul, I agree with the above, lots of detail there. Roy
  12. David is the attached image the feature you're talking about? If it is then as far as I know it simply provides controls for slewing the scope, and has no bearing on the guide rate. I use it occasionally if the scope needs nudging to clear excessive backlash, but otherwise it plays no part in the calibration or guiding. I believe there is an option for disabling it, but I can't quite remember where it appears. Roy
  13. After a great deal of thought and hesitation, I've finally removed the IR cut filter on my 1100D. It's a fairly straightforward job and would have taken no time at all, except for the excessively tight screws holding the case together. I managed to strip the cross heads on three, but was able to drill out the heads and once the camera case was open it was easy enough to remove the threaded shanks. Luckily I've been holding on to an old Canon film camera, which I was able to cannibalise for replacement screws. Despite a few expletives and tense moments it was worth it and I'm pleased with the results. This image of IC 1396 is my first with the modded camera, and because of the cloud I only managed to recover 8 lights for stacking. The nebula was barely visible in the stacked image from DSS, and to produce anything at all I've had to stretch the image to the point where the brighter stars are burnt out. I'm looking forward to a clear night and more data. Thanks for looking.
  14. Some users have found that versions 1.13.3 and 1.13.5 report star saturation when guiding. As far as I understand it, when saturation occurs the software is unable to determine the star centroid and that reduces the accuracy of the guiding, which becomes erratic. The problem doesn't arise with version 1.13.0 and earlier.
  15. I downloaded 1.13.6 ready to install and try tonight, but I wont bother if the star saturation fault hasn't been fixed.
  16. I'm sure your'e right about the advantages of a modified DSLR, and as Gina has pointed out it should be possible to make colour corrections. I've been going through your posts on modifying the 1100D Gina, and it seems to be a manageable DIY job.
  17. This is my first image of the North American nebula, at least a small part of it - with my set-up it could be a good subject for a mosaic. The colour is quite pleasing, especially the blue haze around the brighter stars. That brings me to a question: the camera is unmodified and I was planning to remove just the IR cut filter (the one closest to the image sensor), but would the greater sensitivity in the red part of the spectrum mean that other subtle hues would be lost ? Any thoughts would be welcome.
  18. I don't know the technical details, but DSS prior to the beta version doesn't like the latest .crs files used by the 1100D. I had exactly the same problem until I moved to 3.3.3 beta 45. Roy
  19. That doesn't look over-exposed or particularly noisy, in fact I'd be really pleased with it. Love the star colours.
  20. Whoops, sorry about the image placement!
  21. I'm not sure how much I can add to this, but I find that it helps with star colour to select the "use RGB background calibration" option in DSS. The attached image has been through preliminary processing using a freeware program called Fitswork (easily found via Google). I use Fitswork mainly to flatten the image by removing gradients, but it also has colour correction options, including a saturation control which effectively enhances the star colour. You can see the result in the attached image, which is straight from Fitswork without any additional processing. Roy
  22. How very thoughful of you to point that out, I'll see what I can add. Roy
  23. Thanks for the comments. It's my understanding that the anti-aliasing, low pass filter, also serves as an IR cut filter and I'm hoping that leaving it in place will prevent over-saturation in the red part of the spectrum, but any advice from a modified 1100D user would be appreciated.
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