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Everything posted by sshenke

  1. almcl, thank you so much. Your solution works.....!!! have a great day!! btw, can I ask what the purpose of those group tabs is.
  2. ok, thanks. They do match. very frustrating indeed
  3. yes I did, then selected a reference frame and then re-registered using teh reference frame
  4. Hello, can someone help please. Deep Sky Stacker is not processing my dark or flat frames at all. Even though it recognises it when first added, it doesnt produce master files and when I start the stacking process, it says that there are no dark or flat frames as seen in the attached screenshot. Not sure what I am doing wrong. Would appreciate your help. Thanks
  5. Thanks, I will look at the rotation of the fw. Had very clear skies last night, but did not get any proper images at all. I can see the arc more clearly in the pictures of the pleiades and I can see the same sort of smudge in the picture of M33 ( that picture is a 120 sec exposure of M33!!!!). Looking through the objective port of the scope, I noticed that the secondary mirror is off centre, so I think collimation is definitely a problem. I can also see the bevelled edge of the secondary mirror being prominent and I wonder if there is light coming from the primary mirror that is being reflected off this bevelled edge on to the camera causing the arc.
  6. I am not sure if thats the case, because of 1. why would the dew always form on the same place- the optical window of the ccd camera looks clean to me 2. If it is because of dew, I would expect the images on the second round to be worse because of dew getting worse the longer the scope is outside. This is what I think, may be I am wrong, but thanks for looking into this issue. Really appreciate it
  7. Thanks Carole, yes this is what I have been targeting primarily, as it was an easy target to acquire, given the problems I have been facing. But I did try a few other things like veil nebula, but have not been able to do any substantial imaging with these targets because of the cloud cover. I am going to try again tonight with a differ ent target
  8. Hello all, I would appreciate your help on this problem please. I have been having a huge problem with capturing dso images since October last year, having previously managed to obtain good images of a few galaxies and nebulae ( I started doing this in July last year). For the last few months though I haven't captured even a single decent image and have been blaming the dew, refractor, filter etc. But finally I seem to have got to the bottom of it or so I think. As you can see in the attached images, there is a crescentic area of artefact near the centre of the image. Initially I thought it was the filter, but when I imaged without the filter, it is still there. I cannot see any obvious problem in the optical window of the CCD sensor, but still cleaned it properly with isopropyl alcohol and went onto test it last night and noticed this weird thing. I took 2 round of 1 frame each of lrgb images of m31. I didn't touch the scope or the capture software until the 2 rounds were completed and what I notice is that the smudge was there in round 1 images ( postfixed 1..red1, green etc), but not in round 2 images. I am not sure if it is due to drop in visibility as there was some cloud cover during round 2. Also I cannot see this artefact on images taken during daytime, such as of the sun. It moves independently of the image with the movement of the telescope, which is why I think it is on the CCD camera. This is ruining the images significantly and the unpredictability of it occurring is another frustrating thing. Would appreciate the help of the experienced and the wise please. The image with the title of andromeda 1 was taken about 2 months ago. I have also previously cleaned the primary and secondary mirrors thinking that that's where the problem was. Scope: sky watcher 130 pds Zwo asi 1600mm camera Thanks
  9. Thanks Vlaiv and Billy, I will switch to the 16 bit mode tonight and see if that makes a difference. What do you think about the histograms of the asi1600 and asi120, in the images posted above?. I never get a good histogram with the 1600. as for the dew heating, yes i have used a circular heating pad ( they use it for brewing!!!,) to the back of the primary and it stopped dew from forming, although now i am wondering if dew was present in the primary at all.
  10. Hello all, I have been struggling to obtain good images for some time now, which I have asked help with for , as in the following post: https://stargazerslounge.com/topic/342321-poor-image-quality-cause/ I thought that dew was the problem, hence I posted in this thread discussing about the merits of buying a refractor instead. Previously I was absolutely certain that there was dew on the primary mirror, but I am not sure now. In fact the dew that I noticed on the primary mirror was seen as soon as I had brought the telescope indoors, so it is very likely that the dew had condensed on the surface when it was brought indoors rather than while it was outdoors. Last night has been another disastrous (sorry for the pun!) session where I could hardly see the M31, this is really perplexing to me. Interestingly, the guidescope seems to produce better image than teh main camera as you can seen from the attached images: The ASI 120 mini is the camera attached to the guidescope and the ASI 1600MM pro is the main camera attached to the telescope- skywatcher 130PDS. For the same exposure time, or even less, the guidescope camera collects more light than the main camera. I am guessing that this shoudl not be the case? I wonder if anyone can shed light on this problem please. Thanks in advance
  11. i was thinking about cleaning the primary mirror as well, although it doesnt look too dirty.
  12. Thank you both. there are no water bodies nearby and i can't think of any local factors that might impact on dew formation.
  13. I am not sure if it is anything to do with location. I live in the Midlands ( milton keynes).
  14. Thanks. I left the rear end open, so as to use the fan with or without heating mode, in case the wrapping didn't work. Will close it off as well and see if it works. Thanks. B
  15. Thanks Ian, i am going to try the diy dew shield as well
  16. Thanks, well for what it's worth, I have wrapped the tube, even if it looks absolutely ridiculous!! I had checked the guidescope objective on last Monday and actually it did not have any dew on it.
  17. Yes, absolutely, i have attached a picture i took a few weeks ago looking down the ota
  18. i understand what you are saying. i wondered about that too, as i cannot see what's going on with the secondary mirror. however, it is absolutely clear that the main mirror dews up within a maximum of 1 to 2 hours. I have been using a fan with heating option to blow air from behind the main mirror, not directly down the tube from the front end
  19. Carole, this is really puzzling for me, i have draped the sw 130 pds in exercise mat when i took it out on Monday evening. i will post the picture later, might be hilarious. Temp on Monday evening was 1 to 2 degrees at 8 pm. mirror dewed up promptly within 1 hour. never got to see a single image of interest. Can I ask, if the sw 130 pds you used, worked well in winter too?
  20. i understand what you are saying. i wondered about that too, as i cannot see what's going on with the secondary mirror. however, it is absolutely clear that the main mirror dews up within a maximum of 1 to 2 hours. I have been using a fan with heating option to blow air from behind the main mirror, not directly down the tube from the front end
  21. Thanks. I was certainly happy with the images produced using the sw130 PDS until a few months ago, but not any more as I have made hardly any image worth the effort I had put in, because of the dew problem. It is really puzzling to me as every post I have read says how rare it is to see dew in the primary mirror of a reflector. Not sure if I am doing something wrong. I have tried hair dryer and fan heater ( blowing gently from a distance of about 30 cm) as well. Usually this leads to loss of focussing and it takes about 10 minutes to get the images back into focus, so not useful. I am going to try the insulation mat and dew shield/ cap idea as well next time there is clear sky, before deciding to buy a refractor.
  22. I do have the book, electronic version, but must admit that I havent read it properly yet. It seems well written, glancing through the different chapters. Will read it at some point when I find the time. Happy reading!!
  23. Thanks everyone for your helpful advice. Yes, the 130 pds has metal tube. I will cut out foam mat to cover it wherever i can. in terms of dew shield, i was informed that the ota tube itself acts as a dew shield for reflectors. I shall give it a go, but if it doesnt work, then will buy the refractor. thanks once again
  24. I have been fed up with dew build up on my reflector- Skywatcher 130PDS with no comprehensive solution to this problem. Every imaging session I had recently had been utterly ruined by dew build up within a maximum of an hour. hence thinking of buying a refractor scope instead, as I think dew will be much more manageable with the use of dew shields +/- dew bands. Would appreciate suggestions for a refractor scope for a modest budget (around£500) please. Thanks.
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