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alacant

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Posts posted by alacant

  1. 22 hours ago, DeCosta said:

    taking the camera back to the UK

    Hi
    In Spain, maybe call Luis at str-astrum who may be more knowledgeable as to your climatic conditions.

    FWIW, for cooled CMOS here in Alicante, we've standardised on -5º all year round. In summer it's not easy maintaining much below -10º anyway and the benefit it brings is negligible. 
    HTH

  2. Hi

    I don't think a change of glass will make much difference, but a triplet may.

    Ideas. Use a:

    • focus mask to get you close to focus, then remove it. Use live view to move away from that focus point until the blue halo is reduced.
    • reflector
    • #8 and correct the colour cast afterwards


    Or just mask and reduce it:
    p1.thumb.png.411b8cbc9567d89458d9b79c42c22b89.png

    • Like 1
  3. 2 hours ago, Andy56 said:

    Siril batch Banding Reduction on these files to get a new set of FITs

    Hi

    Siril flips the images.

    Is there any reason for not using Siril to process your cr2s from start to finish? 

    Siril's banding algorithm is best applied after pre processing the fit sequence. You need only a flat frame stack which has had the offset subtracted.  

    Details here.

    You are free of course to flip back or choose any orientation you like. Probably easier though to do it after processing.

    HTH

  4. Hi everyone
    First night for ages I had a telescope to myself. In fact two. Cheepo specials; a gso203 and a Bresser 203.

    m106, ngc2903, m63 and m66, changing to the gso after 106. Forgot to take flat frames, so had to guess the camera angle for the Bresser. Hopeless. The only way out was graX's AI, which I really don't like. Ironically, I think it has the best background. 

    Thanks for looking. 

    3-106.thumb.jpg.50bc470c3c9054046f28ed62b9e04485.jpg

     

    3-2903.thumb.jpg.5c063b973386d53018fed36a95d05e53.jpg

     

    3-63.thumb.jpg.c80bf5d8283c364f0f18be690a896bcc.jpg

     

    3-66.thumb.jpg.dc80c9fb1b41280a5ed0b0a08843665b.jpg

    • Like 10
  5. 1 hour ago, TiffsAndAstro said:

    don't think i saw anything about trying iso800

    To reseat the front element, simply loosen its retaining ring until upon shaking the lens, you can hear it rattle. Now tighten the ring until the rattle just disappears. That should help with the astigmatism/gulls/birds.

    ISO800 is the optimum setting for low noise on the 18mp sensor.

    • Like 1
  6. 18 hours ago, mikeDnight said:

    What's the point of the Bortle scale?

    People seem obsessed with it. I image. To me, it's useless. Where I live, I can see the milky way. But if there's a moon, haze or I've been looking at my 'phone, I can't. I don't need a number to associate with these observations.
    But... Is it a 'good' night if I can see the milky way? No idea until I've assessed the seeing. If it's poor, no amount of Bortle is going to change it.
    Cheers and clear skies.

    • Like 4
  7. Excellent image. Loadsa detail you don't usually see.

    I'm absolutely useless with colour, but had a go HOO. It may help in controlling the red a little. 

    Cheers

    **@stu: have you had a go at this with the same filter on your f4? Should be an interesting comparison.

    Autosave001-a.thumb.jpg.949613aa91752aea5684b00931ff496b.jpg

     

    • Like 1
  8. 25 minutes ago, Kon said:

    For my 12" (f5) i should have the offset (fast).

    Yes. My bad. I read that the 8" was f5 and the 12" f6. f5 is offset. f6 is much more central.
    But the method I gave to adjust the secondary is still correct; the secondary is both too far toward the primary and is rotated incorrectly.

    Cheers

    • Like 1
  9. 1 hour ago, Kon said:

    it seems to be a secondary 

    Hi

    The main difference between f5 and f6 is that for the latter, you'll find the primary donut reflection will collimate almost centrally, with very little offset. You have it set (perhaps by habit?) more as if it were at f5. Primary visibility is not helped by the small secondaries fitted to sw Dobsonians. The fix is easy:

    1. Move the secondary toward the open end of the tube a few mm. To do this, loosen the three secondary adjusters and turn the central screw clockwise.
    2. With the secondary adjustment screws still loose, rotate the secondary until it appears circular. Relative to your photos, you'll need to rotate the secondary anti-clockwise.

    Repeat 1 and 2 until you can see the missing primary mirror clip. Now you will be able to complete the collimation

    Focuser? Be sure to read the common collimation myths and Seronik's no nonsense collimation guide.

    Note that the fast and slow photographs in the AstroBaby guide are incorectly labelled. They should be like this (you're aiming for the slow version):

    fast:

    p1.png.f604c6cc096c2cbf7818a1a231c1ec9b.png

    slow:

    p2.png.fdcc1a644a82972402e1ad3a5f5062dd.png

    Cheers and HTH

    • Like 1
    • Thanks 1
  10. 4 minutes ago, v4169sgr said:

    I estimate 56-57 mm between the image plane and the M48 thread.

    Therefore, and as your images show, apart from tilt, you are too close. Can't recall exactly but we needed at least 58mm from the shoulder of the m48 thread. The m48 t-ring alone will give you 55mm. With your 2mm spacers that's probably around 57mm, but you're now at the safe thread limit. Baader give 57.5mm. Use 58mm as a starting point. The low profile t-adapter with a set of extension rings makes this easy.

    9 minutes ago, v4169sgr said:

    is it really legitimate that the MPCC II doesn't remove all the coma

    It removes the coma, but introduces astigmatism. If you want out-of-the-box-corner-to-corner over aps-c, perhaps consider the GPU.

    Cheers and HTH

  11. 11 hours ago, v4169sgr said:

    software

    Hi
    If you're able to reach focus with the clicklock, then it looks just about as good as you're gonna get. If not, use a low profile eos-m48 adapter and a 12mm extension tube.
    The tilt was measured using Siril under Ubuntu 22.04.3. The same version will run under Mint but if you're interested in the journey as much as the destination, you may wish to build the latest version from source. Testing and reporting bugs helps the developers toward the next release.
    HTH

  12. On 13/02/2024 at 22:02, v4169sgr said:

    Is there any improvement in the second image

    Hi
     

    Excellent shots, but if you feel you want to take it further...
    Both images are tilted; make sure that the primary mirror is adjusted correctly and ensure that the camera-cc assembly be inserted correctly into the focuser.
    Baader cc? Lose the m42 adapter and go with 58mm from the m48 shoulder. If your focuser has a compression ring, avoid clamping across the shoulder of the undercut of the cc. Or just remove the compression ring. Simply dismantling and re-seating usually helps.

    But hey, 450d on a 200 f5; if you're satisfied with the images perhaps stay as you are.
    Cheers and HTH

    p2.png.649b4b2aee46f3403560747563cb2b31.png

    p3.png.41044f8705db007b1b688ae099f9509d.pngp3.png.41044f8705db007b1b688ae099f9509d.png

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