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Found 10 results

  1. Hi, I want to place a CCD camera where the secondary mirror is, remove the sec. mirror completely. It,s a home made F5 14 inch. Do I have to use a coma corrector or/and a field flattener? Can I use a Barlow with a field flattener or coma corrector, can I use eye piece projection with a field flattener or coma corrector? Many thanks, Markus
  2. i am looking for a coma corrector for astrophotography, i have a skywatcher 254/1200 pds, a nikon d5100, and a skywatcher off axis guider, what would you recommend?
  3. Hi all, yesterday caught a good clear sky, so went out to observe. Had a lot of difficulty setting up the scope... On the first run it didn't want to complete the 3 star align, so I had to do everything again, and fortunately, afterwards it did align... Probably to do with poor PA... I had difficulty the first time aligning well with the polaris... So then I tried M1 (was low, and the photo did not turn out too well, so not posting), M64 and NGC 5033 (not processed yet). M64 came out like this without flats: and with flats: As in the last time, big problems with tracking and coma, apart from the flats problems (really have to get me a flatbox). The galaxy is not too bad, but the edges of the photo show terrible stars... Will have to try more and harder... I'm also thinking that in the end the place where I observed (close to home) is not near as good a place for dark skies, as the place from my last post (with M3, M81/82 etc), which is at an hour's drive... http://stargazerslounge.com/topic/240657-coma-problem/?p=2621703 Any thoughts? Any suggestion would be helpful... Thanks! Gerhard.
  4. hi all, I was just reading up on optical aberrations, and it appeared to me that maybe my pics taken with my Vixen suffer from coma... It looks to me like the stars are all malformed, and maybe this is coma, very common to newtonians... Coma correctors can be a solution, as I gather, but backfocus issues might ruin this, if there is not enough room to focus with a corrector on. Does anybody know if my Vixen R150S can handle a coma corrector with a DSLR attached? or will I not be able to focus anymore, and so would have spent 160 euros in vain? I haven't found info on the backfocus of my scope... Any info would be great!!! Gerhard. ps: also anything you might have to say about my pics would be appreciated! :-)
  5. Hi all! Yesterday good weather, so had my first go at drift alignment with my new reticulated eyepiece. I took my time to figure out well the various steps in the right order, etc... At one time, pointing a star in the east, I think I overdid the correction on the Altitude, because the star started drifting a lot, so I started again from the beginning... As always a learning curve! :-) But I had fun doing it. It took me a lot of time, but finally I got to shooting some subs, and these are the results: M57 @ 38 second subs: M13 @ 63 second subs: The usual coma problem is visible, but I am nevertheless quite satisfied with this first try... The stars look pretty good, if not enlarged too much ;-) Opins? Any feedback would be appreciated! Gerhard.
  6. Hi all! Yesterday evening I finally was able to have a success with my new setup. Since february / march I have been struggling with getting autoguide up and running, but due to various mishaps and lots of bad weather, I haven't been able to produce a single image, up until now. This is what came out: M13. As you can see the stars are not very clean... So guiding apparently wasn't as good as hoped for... I also used flats, but there still is a bit of a gradient, but a lot less than previous. These are 180 sec exposures at 800 ISO, so I guess I have to be at least a little bit happy with this result, because without autoguide I could go up until 90 secs, approx. Any thoughts on what can influence good guiding? FWHM was around 5, so not perfect... maybe that could be better, but I never seem to be able to go below those numbers, and often in the past it was way higher... yesterday morning I wanted to set the focus point on the guide scope, so I pointed the moon during the day, and focussed it as best as possible, and marked that on the scope. this night, focus was in fact very close to that mark. But FWHM says it wasn't perfect... I also did drift alignment beforehand, and the guide error graph in Maxim was pretty nice, after initially having to redo the calibrate, because "guide star faded". There were no clouds, however, and the images from the guide scope showed good clear stars (I use a dew shield on the guide scope)... Any idea what this could indicate? I collimate every time, so that should not have been a problem either... Any thoughts much appreciated!! :-) Gerhard.
  7. Have you ever thought about why your Newton telescope has the dimension it has, primary and secondary mirror, focuser, f/number and so on? I stumbled in to this tool Newt-Web that Kenneth H. Slater has developed further from Dale Keller's code. It's an online design tool page for Newton telescope. It's a very intuitive page where you can put in some figures about a Newton telescope that you want to built and get back information about it's performance. It give a ray trace and important data back. From that you get understanding when a Newton telescope design is good or not. I have done some test and written it down on my homepage so you can see the different steps and my comments: http://astrofriend.eu/astronomy/projects/project-design-newton-telescope/project-design-newton-telescope.html I already know some of the physics and math, but never got to know so much in short time what happens when you change a parameter and what happens inside the telescope. Beware, I'm still in the learning process and not all what I have written is fully correct. I recommend you to take a look at Newt-Web page even if you never will built a telescope, you get knowledge and understanding that could be very valuable when you shall buy a Newton telescope. /Lars
  8. Hi all! I was just wondering about something, and would much appreciate to hear some opinions /suggestions... Premise: I'm just starting, very green, and very curious... With my f5 Newton and DSLR I have been getting some very satisfying results so far, apart from the expected coma and tracking issues. I was wondering if it was at all possible to have more magnification with such a setup, to be able to catch also the smaller DSOs... I have been told that those smaller objects are difficult in that one needs longer focals, and thus longer exposures, and thus better guiding. So, just slapping on a barlow between the tube and the dslr would only frustrate things, apart from focussing issues... Can anyone confirm this? This is obviously a long term issue for me, as at the moment, I'm quite happy with the setup I have, and the lack of funds for now puts any ideas I might have on hold. But for the future it would be very interesting to know what options there are for really far DSOs... I would definitely first of all start with setting up auto guide (not just for far DSO), so guide scope, guide cam and PC + connections and software. That's a big bite. Afterwards it would probably be: buying a purpose scope for deep DSOs, long focal, big aperture. SC? RC? A good APO? Opins? thanks all! Gerhard.
  9. Good day all, During the first half of June I worked on this 4 panel mosaic of the LBN 239, 241, 243 complex in Cygnus. Besides the bright component ic1318a it was a test for my new asi1600 on some fainter nebulae. I think the small cmos camera is holding up pretty good. Very little noise, I did not use any noise reduction in the post processing. The calibrated frames have been stretched and stitched together in PS. Details: Scope: 10" f/3.8 Newtonian CMOS: ASI1600MM-Cool @ -20°C Filter: Astrodon 5nm h-alpha Exposure: 20 hrs total (5 min subexposures binned 1x1); Unity Gain setting / 5h for each panel Resolution: 0.82 arcsec/pixel A higher res version can be found here. https://pietervandevelde.smugmug.com/Pics/Deepsky-1/i-MpNmG6t/4K Thanks for taking a look, Regards, Pieter
  10. I am looking for an epsilon 130 (new version). The price must be around 1500£ including shipping to London. General conditions must be good but few scratches won't be a problem. I am not interested in accessories but if you have rings or electronic focuser we may talk. Corrector to canon adapter is warmly welcomed.
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