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Posts posted by Uranium235

  1. Had to get a bit sweaty over this one, lots of star control required. Also, in OIII there is a noticeable halo on the bright star once heavily stretched (nothing can be done about that) but I modelled the backround for that area and subtracted (in Ps) for an overall flatter OIII layer. Tried to retain some decent star colour while I was there.

    I know theres a fair bit of Ha lurking, but in an effort to keep the overall noise down I'll be slightly more restrained. The image should tolerate some pixel peeping too :)



    • Like 7
  2. Looks consistent with tilt.

    A fully loaded imaging train acts as a lever under gravity. So any movement in the focuser or imaging train would be exposed.

    But, I take CCD inspector with a pinch of salt. You would need to take multiple shots of different parts of the sky (but not go past the meridian) to see if the readings are consistent.

  3. DIfficult to see since you havent poseted a full screen shot. But from what I can see it is tilted to one side a little.

    Even my Star 71 needed its focuser (which was also R&P) tweaking out of the box, there are two bolts on top of the focuser- you may need to nip those up a little (and I mean little).

    You can check for focuser movenent by racking it out a bit - then basically give it a tug in all directions. If you detect any movement/wobble (no matter how small), then it needs to be tightened up.

    Still needs to be in focus though to make the correct assessment, before you do any adjustments.

  4. You only need to adiust the flattener if you have introduced a filter into the imaging train or had the camera modified (filter removed).

    Making the spacing longer will only make it worse, it needs to be shorter. Or in focus. The spacing as detailed by FLO is 11.4mm, however that is the recommended distance, and not every camera/filter combination is the same, so you may need to tweak that by a mm or 2.

    But, only from a properly (centrally) focused image can you make a proper assessment and decide which way to go (longer or shorter).

    When focusing, zoom right in to the diffraction pattern... not on the camera screen but using either EOS tools or something like APT. Then, after 45 min or an hour... do it again. (especially during cold weather).


  5. Ok, looking at that image... it is out of focus, but it does display corner characteristics (the distortion is of equal magnitude in all corners) that tell you either:

    1) The FF/FR spacing is too long


    2) The optics cannot provide a (perfectly) flat field across APS-C or larger.


    But, get the image in proper focus first - that might correct a lot of the issues.

    • Like 1
    • Thanks 1
  6. Looks like tilt in the imaging train, being as it gets progressively worse from left to right. However, there is a tracking error in there too.

    1) Check for saggy or loose connections.

    2) Take shorter subs to get an image free from tracking issues (or get guiding) - that will allow you to correctly judge where the tilt is.

    3) Inspect the corners of the test sub, make adjustment as required

    4) Rinse and repeat until satisfied

  7. The sky was just too good to say "no" last night, albeit quite cold!

    So, I set up for shot at this one and took as much data as possible before it disappeared behind the neighbours house (my southern view is quite restricted, 2.5 hours at most). Decided on the 130pds as its in a good, settled place at the moment and performing (as usual) waaaay beyond its price tag.


    14x600s (Ha) 2x2bin (3.4" p/p)

    130pds, NEQ6, QSI683


    Thanks for looking! :)




    • Like 14
  8. Its that time again! :)

    Please use this thread to showcase your best images captured during 2020 (we've all spent a lot of time at home during 2020, so I'm expecting some good stuff). Just one post per member but you can include up to 5 images if you want.

    The thread is for all imagers, both novices and advanced.

    Please keep details to a minimum - scope and camera possibly along with a few comments if required.

    The thread needs to be packed with images so please don't respond to the postings. The previous years showcase thread(s) can be found here:


  9. 23 minutes ago, Jamgood said:

    How did you mask off the primary? I've been thinking about this lately. Better collimation has helped a bit but I'd like to rid those mirror clip spikes. 

    Stars look great is that image. Well done. 👍

    It was about 20mm, which takes it to f5.9. Not really any meaningful difference to the amount of exposure I give it.

    Masking off Ive found, does make collimation easier too. All it is is just a black cardboard ring, that ive stuck to the mirror clips. Simple, but effective. We all know that systems that are of a higher focal ratio have less coma, so... what about adjusting it to a slightly higher (but tolerable) FR so there is less work for the coma corrector to do - in turn giving you a larger useable field.... in this case 100% coverage of a KAF8300 (22mm diagonal).

    However, a complete new set of flats would be required.

    • Like 1
  10. Inspect your flats, a normal one (albeit my example is mono) should look something like this (vignetting amount will differ between optical/camera setups), but it should measure 1/3rd of the histogram - or/and have a healthy ADU reading, over 16bit that would be reading of about 21,000.

    But the previous suggestion of inspecting all your lights should also be done. If you have Ps, then you already have all the tools you need to process the image correctly (after calibratrion and stacking). Dont rely on software to correct vignetting, the only sure way is with proper calibration. If you have a gradient after applying flats, that is best dealt with using a Ps action/filter - or you can create your own gradient map in Ps (a poor mans version of the DBE found in Pixinsight).

    Also, if you want to simplfy your data for now - just convert it all to mono (including your flats), see if you can get anything out of it that way - I find mono is far easier to work with if youre trying to rescue some data.


    • Like 1
  11. 2 hours ago, LooseFur said:

    yes, same lens but I am on full frame so I am not sure how much of the lens area you are using with your camera ? Is it full frame?
    Though I am very new to all this so I have a lot to learn! 
    I opened a thread about this on CN actually (https://www.cloudynights.com/topic/734450-issue-with-asymmetry/). I can't seem to get both corners sharp (top right, bottom left)

    Im using the KAF8300 sensor - its just very slightly smaller than APS-C

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