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JohnSadlerAstro

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Everything posted by JohnSadlerAstro

  1. Thanks! Yeah, those are well written and explained. I wouldn't recommend trying my method for now, it needs some more work to 100% prove that it works and to sort out some miscalculations etc which cropped up! John
  2. Hi, 1. The collimation was "correct" according to the Cheshire on all of the images, with the secondary centred and the primary dot lined up etc. However, it has been around 8 months since I collimated last, and I think things have drifted a little, theres a tad more coma than usual in some parts of my latest subs. 2. I'm planning to re-collimate next week in time for the new moon using this method so I will post up some shots once its properly done, but here's what it looks like atm. John
  3. Hi, As far as I know it isn't a standard method of collimation, I had to develop it after my Cheshire showed the scope as collimated but my subs showed severe coma and distortion across the upper right hand third of the fov. This drawing sort of explains the idea, sorry about the quality! The main concept is that coma and *secondary* light-cone misalignment are related when primary misalignment is removed. Image coma and vignette are in the same places as each other, when the primary is collimated relative to the secondary. In other words, the method can only adjust the secondary and therefore requires use of a Cheshire to keep the primary constantly aligned with the secondary throughout the process. To get a flat, I simply take a quick shot through the scope with my laptop screen open in Notepad, and then take the result into GIMP or StarTools to do a full desaturation and a savage clip/stretch. This was the result from the scope before any secondary adjustments, bear in mind that at this point it was "perfectly" collimated according to the Cheshire *and was rotated/centred almost perfectly, too*. The dark gradients were indeed in the same place as the bad coma, and they fell in the position I had predicted. As shown on the diagram, I then worked out which direction on the photo was which direction for the secondary, then started to adjust. Throughout the process the corrections were perfectly logical and followed my 'hypothesis'. Note that the same stretch has not been applied to each flat, I altered the black point etc to optimise each one for the section I was trying to clean up. Shots 1-3 below show me getting the vertical (horizontal for the secondary) axis correct, then numbers 4-5 show me rotating the secondary into place. After a bit of work I got this ^. Most of the adjustment I had to make was rotation on the secondary, (up is to the right on the photos, so it was drooping a bit) and a little bit of centring with the vanes; I made sure that the primary was correctly adjusted after each movement of the secondary before I took the flat to estimate mis-collimation. I was then able to get almost entirely coma-free images. Hope this helps John
  4. Hi, That's looking really good. ? Secondary collimation is a pain with the PDS, I used flats to get the rotation right in the end, and it worked quite well. John
  5. Thanks! I'll keep a look out for that, I'm interested to see what it will look like with more resolution! Eyy, its about time the galaxy gets some attention, searches suggest its not a common target! ? A word of warning--you'll need long subs, as it does have a low surface brightness--mine were too short really and found that teasing out the arms was quite a challenge. Thanks for the likes, kind words and encouragement! John
  6. Hi, I hope you get on well with your choice! One thing I will say about the EQ5-It looks waay better than any other EQ mount on the market! John
  7. Hi, Yes, for size and weight those two are very nicely matched. However, I would just warn you about using the EQ5 for guiding--I tried it and it was quite frustrating, I ended up upgrading to a used NEQ6. It might be worth considering an HEQ5, which is really designed for astrophotography--it is also a bit sturdier so it will be able to hold the 130 really steady. Hope this helps, John
  8. Hi, My first data this year! I cant believe its been so long, but finally I'm back to imaging again! ? The NEQ6 worked a dream, an average of around 1" total RMS over the night, for 4 hours! I was able to keep around 80% of the frames, too. NGC2403, A difficult target that's probably a NASA copy-paste of M33. ???? 130PDS on NEQ6, Guided with ASI120MC and 50mm finder 1000d, 200sec subs at ISO 800, 3hr 30mins DSS, PHD2, GIMP Star Tools It's a really exciting area of the sky, loads of galaxies and some beautiful colour contrasting binaries. The processing is pretty awful, but there was a really large gradient on each side of the image that was a big pain to remove and took most of the colour with it. I put picture alongside some 100x100 crops to highlight all the little fuzzies. And then compiled them into a table, because the weather was bad. (Square brackets are my data, SIMBAD and the NED are disappointingly incomplete) It's a testament to the miraculous abilities of the 130PDS that I could catch a magnitude 19.4 active galaxy with very newbish processing, a bad camera and a complete lack of experience over the 12 months. Clear skies! John
  9. Magnitude 19.5 radio source? No problem for a 130PDS! :D All will be revealed later....

  10. Hi, I feel slightly embarrassed posting yet another reprocess of this year-old data, but with the lunar illuminations this week and the bad weather I haven't been able to get and quality data with the new mount yet. I feel this is a big improvement over the old version of this image, the noise is still bad but the galaxies have a far more true-to-life colour balance and the stars are waaay more colourful. Unfortunately the short-ish integration time refuses to give the image the "pop" which I'd like, so I'm planning to do a re-run on this pair as soon as they get a bit higher. The stars have got coloured rings around them, this seems to be an issue with most scopes but especially when imaging with a DSLR. I have reduced the effect by applying a gaussain to a star mask--it works quite well but the stars do tend to swell a tiny. 2.5 hours at ISO800 with 1000d (unmodded), roughly 4 min per sub. 130PDS on EQ5. This was the old version: John
  11. I think not. Really nice starfield there though! The Milky Way is so crowded. ? John
  12. Hi, Another quick update, I got the NEQ6 out in a gap between the big Atlantic showers this evening. I did a quick PA with the polarscope and then went through a 3 star alignment which worked really well. I then got 5 frames each on M33 and NGC891. Im planning to get autoguiding up and then get some proper data on 891 later this week if the weather becomes at all cooperative. Noise in this "target preview" is obviously atrocious, as its only 5 mins at ISO1600! Hopefully with 5 hours it will be better. I didnt bother to guide, so there is also some trailing. I've processed in B/W as the noise is too bad in colour. My plan is to rotate 90 degrees and centre on the bright star above the galaxy to get the nearby Abell in as well. John
  13. To be honest ive never thought of it dropping off...?I suppose I could put the strap around the scope. The focuser is very sturdy, as spillage says. I also use the MPCC which is designed for this kind of focuser, so there is an indented ring around it for the focuser screws to lock into. John
  14. Hi, A quick update on my mount issue progress: I found a 2nd hand NEQ6 which I've bought and got set up with the 130PDS. Hopefully it will be able to give good results as soon as the skies clear! The mount seems in very good shape, although there was a bit of dec backlash which ive removed. The real test will be when I try guiding, though. ? This is the mount next to the old EQ5. The Setup. John
  15. NEQ6 collection day! ???

  16. I collect NEQ6 on Monday!!! ?

    1. ASSA

      ASSA

      Huge upgrade, good luck buddy, hope we will see images from new gear soon.

    2. bottletopburly

      bottletopburly

      Nice one john  ?

  17. I guess I ought to update the 130PDS fanboys enthusiasts about why I haven't been around for a while on this thread, the EQ5 autoguiding kicked the bucket so I'm mid way into the painful process of selling stuff to buy a second hand HEQ5. Hopefully I will be back by Christmas spamming out more sub average shots! This is my latest and most embarrasing result, NGC 7331 and Stephans Quintet. Plagued by massive Dec bounces so only 40 mins went into this. Consider it a preview for next year. However, it did help me solve some big collimation issues, so coma shouldn't be too much trouble when I'm back into imaging. John
  18. Neighbours having large charity party nextdoor so I'm having a funk/soul evening under the stars! :D 

  19. Hi, Im not aware I ever posted this one up--M81 and 82, just over 1 hour 300 sec subs at ISO 800 I believe, unmodded 1000d on EQ5 non GoTo, autoguiding. This is the best result I've got so far, as I've been having big issues with every aspect of the setup since then. However, they are gradually being resolved one by one so any day now it will be back into service! John
  20. Hi, Theres a guy down the end of our road who has talked to the ISS. He's got a quite incredible aerial setup, though! I've never been round to see how it's all operated, radio is something I'm ignorant of. ? John
  21. Wow those images are amazing! I'm really looking forward to the nights coming back. One annoying thing with the 130 is collimation. For some reason I can only get the secondary centred if I off centre the front vanes quite a lot. I guess I'll just have to get some test shots in and see how it does. John
  22. I'm afraid that hint isn't very subtle. @Stu Methinks someone wants to increase their amazing scopes collection...… Of course, I eschew such things. ? P.S. Or are you saying you don't want to? Too many negatives in that sentence. You need to eschew them please. Johns
  23. Perfect clear skies forecast tonight! Time to binge Planets!

    1. Knighty2112

      Knighty2112

      Yes! Come on! :) 

    2. pipnina

      pipnina

      I have lovely, cloudless weather here... The forecast says that goes bye-bye at 23:00 and comes back at 03:00 though ?

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