Page 1 of 2 12 LastLast
Results 1 to 10 of 11
Like Tree6Likes

Thread: Problem with star shape - suggestions please.

  1. #1
    JML's Avatar
    JML
    JML is offline SUPER GIANT
    Points: 11,930, Level: 75
    Level completed: 60%, Points required for next Level: 120
    Overall activity: 0%
    Achievements:
    2 Posts Achievement20 Posts Achievement!50 Posts Achievement!5 Threads Achievement!365 Days+ Registered Achievement!
    Join Date
    Jun 2013
    Location
    Casco, WI by way of NY, CA and NJ
    Posts
    1,024
    Points
    11,930
    Level
    75
    Thanks
    184
    Thanked 245x 215 Posts

    Default Problem with star shape - suggestions please.



    The other night I shot some short exposures of M42 with the AT60ED - AT60 Field Flattener - EFW - ASI1600MM system. The Stars in the upper left section of both images show significant elongation towards the upper left corner while the stars in the other quadrants show distortions but to a lesser extent. I see the problem to the greatest degree with the luminosity filter and to a much lesser degree or not at all with the RGB filters. I don't seem to be able to post an image of the problem right now.

    I am guessing that the luminosity filter was pinched in the filter wheel causing its shape to be distorted. I adjusted the tension on the screws holding the 31mm unmounted filters in place and I will test it out the next clear night.

    Do you think I am thinking about this problem the right way or could there be a different cause for the effect that I am getting?
    BABOafrica likes this.
    John

    Backyard POD Observatory; Telescopes - Celestron C8, AT115EDT, AT60ED, ES AR102, Orion ST80, TeleVue Ranger 70mm, WO 50mm guide scope; Binoculars - Oberwerk 11x70 LW; Mounts - CEM60, CG5, Astro-Tech Voyager 2; Astrophotography Cameras - ASI1600MMC pro, Orion StarShoot AutoGuider.

  2. #2
    jaetea's Avatar
    jaetea is offline Maven-like Entity
    Points: 160,966, Level: 100
    Level completed: 0%, Points required for next Level: 0
    Overall activity: 0%
    Achievements:
    365 Days+ Registered Achievement!750 Days+ Registered Achievement!2 Posts AchievementFirst 1000 Experience Points20 Posts Achievement!
    Join Date
    Sep 2011
    Location
    Honolulu, HI
    Posts
    7,909
    Points
    160,966
    Level
    100
    Thanks
    1,224
    Thanked 3,101x 2,414 Posts
    Blog Entries
    17

    Default Re: Problem with star shape - suggestions please.

    Hi,

    Filter pinching is one of the culprits. The other is something not orthogonal. For me, it is usually my FF that occasionally doesn't seat correctly into the optical train. It may look square but that doesn't mean it is square.

    Cheers,
    JT
    BABOafrica likes this.
    Main: C-stron CPC1100 #2
    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.
    :
    8" f/7.5 Dob mounted Newt AP
    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.
    :
    TPO 6" RC f/9 &
    ES 80mm f/6 APO G&G Scope: Meade 102mm f/7.8
    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.
    Guide Scopes: 70 & 80mm fracs Mounts: C-stron AVX CGEM & GT Alt-Az, Cameras: Canon T3i 2, ASI120MC Binos: 10X502,10.5X70,15X702, 25X100 EPs: ES: 21 100°, 30 82° X-Cels: 9,12,18,25 Clubs: RCA & HAS

    HOME »
    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.

    I never met a scope I didn't want to keep.
    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.
    "My God, it's full of stars."
    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.

  3. #3
    JML's Avatar
    JML
    JML is offline SUPER GIANT
    Points: 11,930, Level: 75
    Level completed: 60%, Points required for next Level: 120
    Overall activity: 0%
    Achievements:
    2 Posts Achievement20 Posts Achievement!50 Posts Achievement!5 Threads Achievement!365 Days+ Registered Achievement!
    Join Date
    Jun 2013
    Location
    Casco, WI by way of NY, CA and NJ
    Posts
    1,024
    Points
    11,930
    Level
    75
    Thanks
    184
    Thanked 245x 215 Posts

    Default Re: Problem with star shape - suggestions please.

    Quote Originally Posted by jaetea View Post
    Hi,

    Filter pinching is one of the culprits. The other is something not orthogonal. For me, it is usually my FF that occasionally doesn't seat correctly into the optical train. It may look square but that doesn't mean it is square.

    Cheers,
    JT
    I think everything is orthogonal as it all screws together. Would focuser sag show this effect?
    John

    Backyard POD Observatory; Telescopes - Celestron C8, AT115EDT, AT60ED, ES AR102, Orion ST80, TeleVue Ranger 70mm, WO 50mm guide scope; Binoculars - Oberwerk 11x70 LW; Mounts - CEM60, CG5, Astro-Tech Voyager 2; Astrophotography Cameras - ASI1600MMC pro, Orion StarShoot AutoGuider.

  4. #4
    UlteriorModem's Avatar
    UlteriorModem is offline HYPER GIANT
    Points: 84,068, Level: 100
    Level completed: 0%, Points required for next Level: 0
    Overall activity: 0%
    Achievements:
    2 Posts Achievement20 Posts Achievement!5 Threads Achievement!50 Posts Achievement!200+ Posts Achievement!
    Awards:
    Most Threads Award
    Join Date
    Oct 2015
    Location
    Tallahasse Florida
    Posts
    16,756
    Points
    84,068
    Level
    100
    Thanks
    2,316
    Thanked 4,196x 3,547 Posts
    Blog Entries
    4

    Default Re: Problem with star shape - suggestions please.

    It's possible. We could make a lot better judgement if you posted an actual image.

    Also have you double checked the spacing from the flattener? The specs state 54.8mm
    BABOafrica likes this.
    Scopes: Orion 130mm APO Triplet, Orion 8" f4 astrograph, 10" RC Mount: Celestron CGX-L Guiding: Orion 60mm f4 scope, Starlight Loadstar, PHD2 software - Cams: Planetary: ASI120mc, DSO:Atik 383L+, SGPsoftware Processing : Regisax, Deep Sky Stacker, Star Tools, Pixinsight Assistant: One very large cat
    ~ Put your money where your mount is ~


    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.

  5. #5
    JML's Avatar
    JML
    JML is offline SUPER GIANT
    Points: 11,930, Level: 75
    Level completed: 60%, Points required for next Level: 120
    Overall activity: 0%
    Achievements:
    2 Posts Achievement20 Posts Achievement!50 Posts Achievement!5 Threads Achievement!365 Days+ Registered Achievement!
    Join Date
    Jun 2013
    Location
    Casco, WI by way of NY, CA and NJ
    Posts
    1,024
    Points
    11,930
    Level
    75
    Thanks
    184
    Thanked 245x 215 Posts

    Default Re: Problem with star shape - suggestions please.

    I should be at 55 mm with the spacing between the flattener and the sensor. still working on getting an upload to work.
    John

    Backyard POD Observatory; Telescopes - Celestron C8, AT115EDT, AT60ED, ES AR102, Orion ST80, TeleVue Ranger 70mm, WO 50mm guide scope; Binoculars - Oberwerk 11x70 LW; Mounts - CEM60, CG5, Astro-Tech Voyager 2; Astrophotography Cameras - ASI1600MMC pro, Orion StarShoot AutoGuider.

  6. #6
    yobbo89's Avatar
    yobbo89 is offline HYPER GIANT
    Points: 20,725, Level: 99
    Level completed: 45%, Points required for next Level: 275
    Overall activity: 38.0%
    Achievements:
    2 Posts Achievement20 Posts Achievement!5 Threads Achievement!50 Posts Achievement!Gallery Achievement!
    Join Date
    Nov 2015
    Location
    brisbane
    Posts
    2,309
    Points
    20,725
    Level
    99
    Thanks
    141
    Thanked 544x 466 Posts

    Default Re: Problem with star shape - suggestions please.

    Focuser slop?

    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.
    :gso/bintel f4 12"trust tube, bresser
    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.
    ar127s /
    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.
    10'' dob
    cameras : asi 1600mm-c/asi1600mm-c,asi120mc,prostar lp guidecam, nikkon d60, sony a7
    mounts : eq6 pro/eq8
    filters : 2'' astronomik lp/badder lrgb h-a,sII,oIII,h-b,Baader Solar Continuum, Thousand Oaks Solar Filter.
    extras : skywatcher f4 aplanatic cc, Baader MPCC MKIII
    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.
    Corrector,
    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.
    Field Flattener,zwo 1.25''adc.starlight maxi 2" 9x filter wheel

  7. The Following User Says Thank You to yobbo89 For This Useful Post:

    JML (11-29-2018)

  8. #7
    JML's Avatar
    JML
    JML is offline SUPER GIANT
    Points: 11,930, Level: 75
    Level completed: 60%, Points required for next Level: 120
    Overall activity: 0%
    Achievements:
    2 Posts Achievement20 Posts Achievement!50 Posts Achievement!5 Threads Achievement!365 Days+ Registered Achievement!
    Join Date
    Jun 2013
    Location
    Casco, WI by way of NY, CA and NJ
    Posts
    1,024
    Points
    11,930
    Level
    75
    Thanks
    184
    Thanked 245x 215 Posts

    Default Re: Problem with star shape - suggestions please.

    Quote Originally Posted by yobbo89 View Post
    Focuser slop?
    I will keep this in mind the next time I am setup
    John

    Backyard POD Observatory; Telescopes - Celestron C8, AT115EDT, AT60ED, ES AR102, Orion ST80, TeleVue Ranger 70mm, WO 50mm guide scope; Binoculars - Oberwerk 11x70 LW; Mounts - CEM60, CG5, Astro-Tech Voyager 2; Astrophotography Cameras - ASI1600MMC pro, Orion StarShoot AutoGuider.

  9. #8
    UlteriorModem's Avatar
    UlteriorModem is offline HYPER GIANT
    Points: 84,068, Level: 100
    Level completed: 0%, Points required for next Level: 0
    Overall activity: 0%
    Achievements:
    2 Posts Achievement20 Posts Achievement!5 Threads Achievement!50 Posts Achievement!200+ Posts Achievement!
    Awards:
    Most Threads Award
    Join Date
    Oct 2015
    Location
    Tallahasse Florida
    Posts
    16,756
    Points
    84,068
    Level
    100
    Thanks
    2,316
    Thanked 4,196x 3,547 Posts
    Blog Entries
    4

    Default Re: Problem with star shape - suggestions please.

    Quote Originally Posted by JML View Post
    I should be at 55 mm with the spacing between the flattener and the sensor. still working on getting an upload to work.
    Uploads are still not working it's not you. You will need to use a third party hosting site such as Flickr.

    Another way would to be make the image available to us in a drop box link.

    Focuser sag is possible, collimation is another possibility, or just plain tilt of the entire imaging train. Again it would be helpful to see an actual image.

    Quick question, how far out is the focuser's draw tube when you reach focus? If it is way out well past halfway you may want to consider an extension ring.
    BABOafrica and JML like this.
    Scopes: Orion 130mm APO Triplet, Orion 8" f4 astrograph, 10" RC Mount: Celestron CGX-L Guiding: Orion 60mm f4 scope, Starlight Loadstar, PHD2 software - Cams: Planetary: ASI120mc, DSO:Atik 383L+, SGPsoftware Processing : Regisax, Deep Sky Stacker, Star Tools, Pixinsight Assistant: One very large cat
    ~ Put your money where your mount is ~


    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.

  10. #9
    JML's Avatar
    JML
    JML is offline SUPER GIANT
    Points: 11,930, Level: 75
    Level completed: 60%, Points required for next Level: 120
    Overall activity: 0%
    Achievements:
    2 Posts Achievement20 Posts Achievement!50 Posts Achievement!5 Threads Achievement!365 Days+ Registered Achievement!
    Join Date
    Jun 2013
    Location
    Casco, WI by way of NY, CA and NJ
    Posts
    1,024
    Points
    11,930
    Level
    75
    Thanks
    184
    Thanked 245x 215 Posts

    Default Re: Problem with star shape - suggestions please.

    Here is a link to two images that show the problem that I have posted on flickr

    https://www.flickr.com/photos/653154...posted-public/
    John

    Backyard POD Observatory; Telescopes - Celestron C8, AT115EDT, AT60ED, ES AR102, Orion ST80, TeleVue Ranger 70mm, WO 50mm guide scope; Binoculars - Oberwerk 11x70 LW; Mounts - CEM60, CG5, Astro-Tech Voyager 2; Astrophotography Cameras - ASI1600MMC pro, Orion StarShoot AutoGuider.

  11. #10
    BABOafrica's Avatar
    BABOafrica is offline Moderator
    Points: 65,967, Level: 100
    Level completed: 0%, Points required for next Level: 0
    Overall activity: 0%
    Achievements:
    200+ Posts Achievement!First 1000 Experience Points400+ Posts Achievement365 Days+ Registered Achievement!5 Threads Achievement!
    Join Date
    May 2011
    Location
    Nairobi, Kenya
    Posts
    7,175
    Points
    65,967
    Level
    100
    Thanks
    1,492
    Thanked 3,251x 2,873 Posts

    Default Re: Problem with star shape - suggestions please.

    Quote Originally Posted by JML View Post
    I see the problem to the greatest degree with the luminosity filter and to a much lesser degree or not at all with the RGB filters.
    I looked at your image. It seems that the elongation affects the left side of the picture, though the upper left is worst.

    If you don't see the problem at all with some filters and see the problem exaggerated with other filters, I would check the "worst" filter first. It may be slightly titled in the optical train.

    Joe
    JML likes this.
    In lumine tuo videbimus lumen


    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.
    : WO ZenithStar SD f/5.9 66mm APO -- Meade f/9 102mm APO -- Celestron SCT C8 -- Sigma f/5.6 400mm APO lens
    MOUNT: Celestron AVX & Atlas EQ-G

    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.
    CAMERA: Fujifilm X-A1 (mirrorless) / Orion-SSAG

    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.
    : DSS -- StarTools -- GIMP -- Bahtinov Grabber 64

  12. The Following User Says Thank You to BABOafrica For This Useful Post:

    JML (11-30-2018)

 

 
Page 1 of 2 12 LastLast

Similar Threads

  1. Replies: 15
    Last Post: 02-02-2016, 12:58 AM
  2. Serious Problem with Setup! Need Help or Suggestions, Please!
    By bowene in forum Celestron Telescope Forums
    Replies: 1
    Last Post: 04-02-2015, 01:51 PM
  3. Star charts & suggestions!
    By simon96c in forum Astronomy Beginners Forum
    Replies: 7
    Last Post: 04-24-2014, 04:38 PM
  4. Suggestions for a Star Diagonal
    By PromisedLand84 in forum Celestron NexStar Telescope Forum
    Replies: 5
    Last Post: 11-05-2011, 09:31 PM
  5. Replies: 23
    Last Post: 06-13-2009, 10:19 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Powered by vBulletin® Version 4.2.0
Powered by vBulletin®
All times are GMT. The time now is 06:40 AM.