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discardedastro

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About discardedastro

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    Vacuum

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    Oxfordshire, UK
  1. discardedastro

    Light leak or something else?

    I've flocked the inside of my tube now - took out the primary and very carefully cleaned it while I was at it. Once I had it all back together on the bench I assembled the camera and took some 60 second and 5 minute exposures. With the scope in a bright room there were similar-looking halos in the frames. Covering the focuser made little difference, but covering the rear of the scope by the primary with a dark coat resulted in perfect frames showing very no sign of any light. So it looks to me like I need to find a way to properly cover the rear of the tube to minimise the risk of light entering the tube and causing these problems again - either I can find an appropriate plate pre-made or get a friend to CNC some sheet aluminium. Thanks all for the help!
  2. discardedastro

    Light leak or something else?

    Right - thanks for all the tips. The scope is set up in my garden but still close enough to the house there are some potential sources of light. I've got the scope off the mount while I fit a focusing motor to the focuser (which has turned out to be Exciting, the Skywatcher focus motor mount does fit, but blocks up the parallelising adjustment screws, so had to expand some holes in that plate with some files and a drill), so I'll go around with a torch on the bench and see where there's potential for leakage. I'm guessing something as simple as a blackout cloth over the back of the primary would be enough to stop any leakage there, though I might be brave enough to pop the mirror cell off and flock around the interior near the primary. The focuser's the other potential entry point - I've now applied flocking around that area to try and minimise the impact of any leakage, but might also paint the (non-contact) external surfaces of the drawtube with some matte black enamel I've got lying around to mitigate bounced light there. Everything upstream of the focuser is sealed and I can take perfect dark frames with the lens cap on the EFW in a brightly lit room, so that lot's OK!
  3. discardedastro

    Light leak or something else?

    I should clarify though that the dark frame (second image in the post) was taken _with the telescope cap on_ - the really bright star on the right, do you mean in the last frame? If so, that's a dark frame taken with the lens cap on the EFW, rather than the telescope cap - I repeated dark frame capture with the camera cooled on the bench after I saw the first dark frames and the lighting issue, and the bright star in that frame is just the amp glow the ASI183 tends to suffer from. So I don't think it's a bright star causing issues - my thinking has mostly been local pollution, lights from near the scope etc. The Baader filters have a black mounting disc and I can't immediately see anyone reporting similar issues with them. I've got some flocking material I haven't yet fitted to the tube, so I might give that a shot - slightly terrified of removing the primary mirror cell to get at it all but hopefully it'll all go back together without too much issue! My suspicion is mostly that there might be light leaking in around the focuser's drawtube (on the outside) that's then reflecting off the secondary.
  4. I've seen an interesting issue with my first few captures; the dark frames and light frames I took with the camera mounted on the scope featured this odd glow towards the middle/left of the frame. Conversely if I take a dark frame with a cap after the EFW with the camera on my desk, I get a perfect dark frame with the ASI183's usual amp glow. Is this likely to be a light leak, or something else altogether? Skywatcher 200PDS, ASI183MM-PRO, Mini ZWO EFW, all clamped up in the standard Skywatcher focuser.
  5. discardedastro

    Next steps...

    Thought I'd follow up on this, at risk of necro'ing a thread - I went for the ASI183MM-PRO in the end and have been very happy with it. The oversampling and narrow FoV make for incredible detail - I've only had two nights with it so I'm still working out the kinks, and the coma corrector is still on its way (along with a Hitecastro DC focus). I got a set of Baader LRGB and mini EFW which appears to be working well, and stumped for Sequence Gen Pro which I got working with EQMOD and platesolving yesterday! First quick image attached, though I've got plenty of PI/LRGB stuff to learn - thanks all for the advice!
  6. discardedastro

    Next steps...

    Coma corrector's an interesting one - have been considering picking up a Baader MPCC or the Skywatcher corrector/reducer, but have only seen a very small amount of coma in my light frames (example attached). I think If I upgrade the camera I may start to notice it a bit more - the D1X may be ancient but it got me making images I was actually happy with and happy sharing (and thanks for the kind feedback!) - it is a bloody old thing though! I've attached a single light frame. I think I'll stick to mono, whichever way I go vendor-and-sensor wise. Some of the higher resolution sensors like the 20MP one in the ASI183 seem promising on paper, and come in at a slightly lower price point than the ASI1600; I haven't quite gotten my head around the whole pixel-size-vs-sensitivity-vs-telescope-f-ratio-and-FoV relationship yet, though. The 200's not ideal for some DSOs in terms of the usual field of view but seems to sit nicely in a price-performance sweet spot for some targets (like M33), but I do want a camera that will be versatile enough down the line. DSC_1221.tif
  7. discardedastro

    EQ8 Electrical problem

    I'd definitely start with a replacement hand controller, just to rule it out - it's a cheap thing to get and the more up-to-date Synscan controller is probably useful anyway if it's not the problem. Beyond that, if the mount is drawing much current at idle (>0.5A) then it might be a short or similar, otherwise likely to be a controller issue either internally or externally. If it's external replacing the hand controller will fix it. if it's internal, off to your fave mount service team it is I think!
  8. discardedastro

    Next steps...

    Hi all, Long time reader, thought I'd post for a change! I've been working my way up to a sensible AP rig, with a focus largely on DSOs. My current setup is: Skywatcher 200PDS Skywatcher EQ6-R Pro mount Primaluce 60mm guidescope and ASI120MC guidecam Nikon D1X (yes, the 17 year old one) camera for imaging Other bits: Hotech laser collimator, Bahtinov mask, Nevada 12V PSU, QHY Polemaster, Astrozap dew shield for the 200P, random PCs, and a Telegizmos cover Software: PHD2 guiding, capturing on the DSLR with a hardware intervalometer, Rawtherapee+DSS+ST for post I spent probably the first year arsing about with the 120MC and not quite figuring out how to drive everything - alignment on the EQ6-R, collimation, _proper_ alignment, stacking, processing, etc. I got DSS and StarTools as a starting point, though considering grabbing PixInsight next year. I'm currently setting all this up just outside my house which is a class 4 bortle area (estimated), and leaving the scopes/mount out 24/7 - so far so good on that front! I'm planning to build a simple ROR obsy next year to save tearing it all down and setting up every night. I got the D1X as a donation last month, and added the guidescope as a Christmas present. With this motley lot I've managed to gather the two attached - M33 was 4 or 5 hours of integration, M31 considerably less and with 98% humidity so quite dewy optics and the fog rolling in! But I seem to be managing reasonably good guiding and stability - M31 was using 2m30s light frames, M33 using 60s lights. The D1X has an ancient sensor and pretty poor sensitivity, plus it has oddly shaped pixels that make postprocessing fiddly. The question really now forming in my head is: where next? I'm largely thinking an upgrade to the camera would be sensible given the extreme age of the sensor. It's been fab having a larger frame and more pixels than the 120MC but getting a back-side-illuminated sensor based camera seems a no-brainer as a next sensible investment, probably followed by a reasonable APO scope (the mid-to-large Williams Optics or Skywatcher Esprits are looking about right in terms of price). But am I missing some sensible small investments, quality-of-life wise? What camera should I be looking at - the ZWO 183MM looks great from a resolution perspective but the 1600MM still looks tough to beat in the sensitivity dept. Some guidance or thoughts on sensible next steps would be welcomed, basically - I've been staring at all the options for a while now!
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