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About crovax

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    Star Forming

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    Kyiv, Ukraine
  1. Uh, well, I've created a median layer but after all the noise didn't go away. I believe that I may have messed up something when taking the photos so I am planning to redo everything from the start. However before I do this, could you please let me know whether the following procedure is correct: take X subs, take X darks, average darks into master dark, subtract master dark from each sub, merge subs using "addition". If I am mistaken here, please correct me. Also I am not sure whether there is some difference when I "subtract" master dark from sub or when use "difference" mode. And the final place where I have doubts is ISO. I've been playing with ISO 1600 but I wonder whether this is too extreme or not?
  2. Oh, never mind, I guess I found the median tool in photoshop. It's located in layer -> smart objects -> stack mode -> median
  3. Hi, Thanks for the awesome explanations! I've already took all the darks and now I am trying to create a master dark of them. Unfortunately I got stuck at this point. It seems GIMP doesn't have this feature (or it is named in a way that I can't recognize it). I found a plugin that is supposed to do this but it is very buggy and I can't get the results out of it. I also tried looking in DSS and Photoshop but still no luck. Could you give me link to Maxim software you mentioned earlier. Also do you by chance know Linux software that can average/median images? My main and the most powerful PC is running Linux and I feel lazy about installing virtual Windows on it. However if this operation is not very resource hungry I can always perform it on one of my old computers that run Windows.
  4. Ohh, that makes sense now! Just to clarify things, "master dark" is the resulting image that we get after combining our X dark frame shots, right? Also I don't understand very well what master bias is and what "subs, plus flats" are? I read about nature of bias noise and article suggests taking shots with 0 sec exposure. I doubt I can do this since my camera is not a pro one, it's a simple canon powershot a580. Is it possible to go with master dark only since as far as I understand it contains bias noise (as well as dark noise)? Or are the bias 0 sec shots a must?
  5. Hi, I've recently went through a wonderful article on afocal astrophotography (Afocal Astrophotography) and decided to try to use the theory I've learned. Well, since I haven't seen clear skies for months already my test object is a book in a dark room. All the photos below are ISO 1600, and 4 sec exposure. I decided to go with 1600 because I thought this would give me very noticeable noise and therefore very noticeable results of dark frame technique. The exposure is 4 sec because I wasn't able to make the room any darker First I took 5 photos of the object. Then I took a dark frame photo. So far so good. Then I went to PC, opened GIMP and put all the 6 images on different layers. For the first 5 I used "Addition" mode and the result is quite expected. And then I tried to use "Difference" mode for the dark frame. I also tried "Subtract" but these two different modes produce result that look the same so I decided to stick with "Difference". And that's the place where I get the unexpected result. I sort of hoped that all the horrible noise from the photo will be gone but this didn't happen. The photo changed a little but I can't tell whether it became better or worse. I've uploaded all my result here Picasa Web Albums - eugene.bondarenko - testing... If you hit "Download" you can get any image in the original size. Could you please tell me what I am doing wrong. Is it because of big ISO? And if yes, how is this noise called and is it unremovable? On the other hand if this is Dark Current Noise after all, then why didn't it get removed after I subtracted the dark frame? Or did I subtracted it in a wrong way? Or is the result not noticeable because I stacked only 5 frames and if I had stacked 100 photos, it would have been noticeable? Uh...sorry for so many questions
  6. I am very surprised with your SNP issues. I have ASUS EEE 900 which has quite weak specs and a weird screen resolution. No problems so far. Except that some big sized info doesn't fit into the tiny display and gets cut off.
  7. I wear glasses but I take them off when I use binos or telescope. I simply find it very uncomfortable to wear glasses and look through EP/binos. On the other hand as JimBobs63 has mentioned another observer will have to refocus after you. And then you'll need to refocuse after that observer. And so on. Also every time I look at the sky to point my 'scope to the right place or to navigate through stars and constellations to find the right place to point 'scope at, I have to put my glasses, then take them off to look into EP, then put them on to point 'scope again, etc. This s*cks very much too. I think that alfi is right, simply try both and you'll know which is more comfortable for you.
  8. Judging from your picture Jupiter looks quite nice and the size is fine. Most likely the Barlow didn't help because the turbulence was bad. In such cases big magnification usually gives a disgusting smudge instead of Jupiter However you should definitely try 10mm+Barlow again. Jupiter is an mazing target for large magnifications. I've been observing it with 4mm and 6.5mm+Barlow and it is totally worth it. On 6.5mm+Barlow I even started seeing features in the bands (instead of seeing them as lines).
  9. Hi, I think you're having the problems because of bad focus. I (at last!) observed sunspots this Saturday with my 130 skywatcher. I tried playing with focus (using 25mm EP) and sunspots simply become invisible if the telescope is not focused perfectly. Try using the following trick. Set up your 'scope, locate a distant tree, focus on it, put on your filter, locate Sun and look into the EP.
  10. Thanks, I also hope that the weather will be nice. Right now all the sky is fully covered with clouds and taking into consideration the current season, the sun can be hidden for weeks now. July sunspots were very disappointing. They disappeared exactly on Saturday
  11. Ohhh and again I am missing the sunspot because it is up during the wordays :( What do you think about the lifetime of this spot? Will it last till weekend?
  12. I dunno, next weekend I'll do my best to find this object again. I guess this won't be very hard because it was a very noticable thing. Not veeeery noticable like Vega but still not a tiny star. IMHO it's impossible to miss it. Then I'll be studying star patterns and making photos and hopefully will get its name. The problem is that I don't clearly see Pisces. I can try to start tracking the object from Aquaris but it is not very helpful too. Only Phi Aquarii is a little close to that area and that star is not much brighter than the stars from Pisces.
  13. This is totally weird, this reddish star was so distinguishable that I was sure it was not a star. This brings back the quest of finding Uranus Also I'll do my best to accurately locate this thing and then will be sketching it to determine if it moves or not. Or even better - I'll be making potos of it.
  14. Well, if no one comes with an idea about this thing untill next weekend, I'll make a photo of this UFO and post it in this thread
  15. Well, that raises another question: what was that? I saw blinking stars caused by air turbulence and this is definitely not the case. It was stable and red. Just like Mars.
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