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Pompey Monkey

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Everything posted by Pompey Monkey

  1. You can make one for a third of the cost of a pre-made cable (sorry FLO!). The most important thing is to get a genuine FTDI USB to RS232 serial adapter. Also, as said above by @dunc check the TTL voltage against the mount specs. BTW, APT is a very good piece of software. @Yoddha puts a lot of work into it and listens to all the user feedback!
  2. Well I haven't posted an image for a long time, sometimes because I am not satisfied with the end results but, more often, because I give up half-way through. Ii's a character trait of mine that I have to keep fighting! Anyway, I've paid a deposit for remote hosting (with a friend) at E-Eye, so thought I'd better start finishing stuff... Here is my take on M45 from the beautiful Bortle 2/3/4 skies over Portsmouth. I don't have the raw data to hand, but it's probably around 10 hrs of LRGB. Equipment as in the signature. Hope you like it.
  3. Not the usual existential version of the question, but a literal one: I've been struggling with my processing ever since I started, but I'm gradually getting better. Thing is, I opened up PI today to be greeted to a super process of a preview from My M81/M82 Lum integration: But I don't remember how I got here! LOL. ?? Answers on a postcard please!
  4. After a "tip-off", I was directed to this thread by the esteemed @gnomus So I swapped my spacers around to put 5 mm between the filter wheel and camera, and what do you know... The line has disappeared off the bottom and nearly wandered off the top, although now I see one on the left more clearly. I am convinced that they will all go with a bit more spacing Bleedin' awful, Guv'! I believe you are exactly correct, @Whirlwind Just one caveat: it's a metal cover plate. This is an SBIG camera, don't you know. Now I just need to get my stars round in all four corners.....,
  5. Yup - it's a mystery! The four-sub stack is calibrated, for sure. I can't help but wonder if the steeper light cone is having an effect: I the focuser is now 4 cm closer to the objective than it was with the SW flattener...
  6. Having just done the usual absolute no-no of changing more than one thing in my system at a time, I've encountered a really odd issue with my images. I am trying out a TSRED279 reducer in on my Esprit 80 ED, to try and get a bit more real estate on my SBIG STF 8300M. I'm also trying out the Chroma 3 nm NB filters at the same time. There are a number of issues to do with spacing and tilt*, but the most puzzling is the appearance of strange horizontal bars on my subs and flats that don't calibrate out. I've rotated the camera and filter wheel in relation to the reducer, but the bars remain in the same orientation to the chip. It almost looks like a knife-edge obstruction, with added diffraction, close to the sensor. Has anyone seen anything like this before? Apart from that, I'm really impressed with the 3 nm Ha filter - the image is 4 20 minute subs, taken last night, about 60 degrees away from a fat gibbous moon. Also, humble apologies to @ollypenrice, to whom I told the other day that I never had any problems with flats... *I'm not 100% convinced that the Esprit, obviously made to a very competitive specification, is actually mechanically able to cope at f4... but I'll persevere for a while yet.
  7. I've seen this before and I think that it was a around the time that I was fiddling with back focus distance on my Esprit 880ED. Have you allowed for the increased optical path length due to the filters? This is usually approximately 1/3 of the thickness of the filters. See here http://www.qsimaging.com/downloads/QSI-500-600-Series-Back-Focus.pdf Also, are the bananas oriented the same all over the FOV, or do they gradually change curvature over the image? If they change, it might be another indication of incorrect spacing between the comma corrector and the imaging plane. Can you post the whole image?
  8. Are you sure it did not actually brush against the mount at some point? The other thing that comes to mind is a less than perfect PA - this is another source of cone error. However, given the quality of your images, I suspect that your alignment is rather better than +- 3/4 of a degree!
  9. I gave this post a "like" because it's obviously well informed. However, everything I've highlighted in red illustrates why the mainstream user does not understand and does not adopt Linux: I know what an "ISO" is, but many wouldn't and I have no idea what the other highlighted terms mean, and I'm an engineer who's been on a Unix administration course! I know that GIYF, but it takes time I want to adopt Linux, but the learning curve is steep and, to be honest, puts me off somwhat. I will, however, persevere. One thing that came to mind to me is to get a secondary system running with mount/camera/obsy simulators until I'm confident that I can diagnose problems and find solutions without wasting night upon night of clear skies before going "live"....
  10. This is a good idea - adding the missing, but necessary, quality assurance. I hope that everyone buying one of these "budget" 'scopes will seriously consider the small extra cost to be a good investment.
  11. Yes! Even more remarkably, I already have the correct spacers for my SBIG CCD/ SX FW combo! That's why I'm buying new: peace of mind. You may, or may not, have seen my thread in "whole scopes" about the second hand Star 71 that I bought a couple of months ago. To my mind it's a write off. Actually, it's worse than that as I've wasted every clear night since the middle of February faffing about with it. Particularly galling as the weather was soooo bad through out autumn... One more question: Do I need a metric or imperial ADM dovetail kit? I'm specifically thinking of the threads on the scope bracket for the low-profile screws. Cheers!
  12. Well that was fourteen long pages.... ....with no conclusion! I have a SW Esprit 80 ED, flattener and extra dovetail (for balancing my filter wheel and CCD) in the basket at FLO. I'm just itching to pull the trigger but have yet, despite numerous excellent astrobin images, to be convinced of Skywatcher's QC... Anyone? FLO?
  13. Lovely - understanding what you are taking pictures of is sadly missing in too many examples nowadays - you have an excellent appreciation of the "bigger picture" as they say.
  14. Hi, and welcome to SGL! Your set-up looks fine. The position that your DSLR finished in is actually a very logical one for balancing and works very well, even if it looks counter-intuitive to the inexperienced. Also, APT is my capturing software of choice and will see you a long way into your imaging career. As you are using a DSLR, I'll add one more thing: dither, dither, dither. Dithering is the best DSLR noise reduction strategy (in conjunction with taking more subs) there is. Dithering works great with APT and PHD
  15. You'll end up either needing or wanting a coma corrector for sure A lot of posters don't mention camera speeds because they use CCDs... Awww - what the heck - it's only 20 mm more - here's my Rosette with the 150 PDS and Skywatcher CC
  16. I was. But now I had a chance to look at the full size image, I agree with you that it looks like a touch of coma. Sorry about that. Have you got the spacing between the CC and the sensor correct?
  17. That looks more like internal reflections than coma to me. Welcome to the world of worrying about second-order effects
  18. Morning Richie, Funnily enough, I only posted about this in another thread just last night: "15 mm movement on a 750 mm focal length telescope is a 2% radius = 4% loss of light due to spillage past the secondary, assuming it was fully illuminated in the first place. I can live with that As for vignetting, I would hope the telescope manufacturers would design for none with the focuser fully extended. I certainly don't see evidence for extra vignetting on my flats. In summary, a small longitudinal movement of the primary is unlikely to have a critical effect on the optical path." I do have the 150 PDS, but the principle is be the same. It's all just triangles. As for the scooping out of the focuser tube.. Well you could always try it and report back your results...
  19. Good old engineering judgement: I'd read that 10 mm off the focuser would fix the "bitten" star feature. Another 5 mm made sure* I'd also picked up my 150 PDS OTA from Astroboot for £113.50, including postage (Brand new, with just a tiny scratch on the tube). So it would only be a little bit painful if it all went wrong. But how could it go wrong? It's just metal tube and some mirrors! *Of course I checked that I would still be able to reach focus first!
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