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Thread: Question about Skywatcher "Panorama" 82 degree eyepiece

  1. #1
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    Default Question about Skywatcher "Panorama" 82 degree eyepiece



    Hi all,

    I had a look through the new Skywatcher Panorama 82° 23mm eyepiece last night in both an f4 newtonian (with a coma corrector) and an f8 refractor, and the field seemed darker in the central 2/3 than the outer 1/3. It was almost like there was a ring of light pollution causing a brighter background in the outer 1/3 of the field. The field was reasonably sharp to about 10% from the edge in the f8 scope (but still with a "ring" of brighter field), but the "seagulls" started to develop around the same area as the field brightened in the f4. (In comparison my ES 100° 20mm showed a sharper field to the edge, and I didn't notice any field brightening.)

    I didn't get to do a great deal of testing as the clouds discovered that we were using some new equipment, so this was from a reasonably quick look.

    I am puzzled as to what caused this. Is it simply that the light is "smeared" due to coma in the eyepiece, making it look like a lighter background towards the edge?

    I would welcome any thoughts you might have.

    Thanks in anticipation.

    - Dean
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    Default Re: Question about Skywatcher "Panorama" 82 degree eyepiece

    Hi Dean,

    My first thought was that it might be caused by the field stop and its position with the EP barrel.

    Cheers,
    JT
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    Default Re: Question about Skywatcher "Panorama" 82 degree eyepiece

    +1 Agree with Jaetea
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    Default Re: Question about Skywatcher "Panorama" 82 degree eyepiece

    Thanks JT and Gabby.

    I was originally thinking there was some sort of vignetting, but then I thought it would be the other way round- darker at the edges?

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    Default Re: Question about Skywatcher "Panorama" 82 degree eyepiece

    Re: a lighter background towards the edge?

    Hello Dean,

    that's a frequently noticed problem with some 82° FOV designs. It may be due to the highly curved thick lenses in the EP passing more light outside of the center field - my guess coming out of the sleeve.
    Even the expensive Morpheus 4.5mm suffers quite noticeably from this problem.

    Best,

    JG
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