Skywatcher esprit100ed

Discussion in 'Aluma CCD Series' started by Dhari, Feb 25, 2021.

  1. Dhari

    Dhari Standard User

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    Greetings

    Camera: sbig aluma 8300 + FW8S aluma
    Telescope : skywatcher esprit100ed
    Reducer : apex 0.65 L version

    Can you help me to find the back focus because starts not round at corners . Or the reducer will not fit with camera ?[​IMG]


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  2. Doug

    Doug Staff Member

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    That isn't a focus problem, it's an off-axis aberration issue.

    This may be caused by the reducer being at the wrong spacing from the focal plane.
     
  3. Dhari

    Dhari Standard User

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    What’s your advice for this issue ?


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  4. Doug

    Doug Staff Member

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    Check the manual for the focal reducer. Talk to the manufacturer of the reducer or your dealer.
     
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  5. Colin Haig

    Colin Haig Staff Member

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    Your Aluma 8300 camera plus filter wheel plus a mounting plate adapter ring (M48 or M42) would require approximately 40.3mm of backfocus.
    That scope and reducer would produce a focal plane somewhere between 55mm and 58mm if my understanding of that equipment is correct.
    So you would need between 15 and 18mm of extra space from the back of the reducer to the front of the mounting plate.
     
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  6. Dhari

    Dhari Standard User

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    Thanks for fast reply


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  7. Colin Haig

    Colin Haig Staff Member

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    Also, you should probably be using the field flatener made by Skywatcher that is matched to it's optics. There is one for that specific telescope.
     
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