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Thread: Eyepiece selection by telescope type

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    Default Eyepiece selection by telescope type



    Does anyone know of a reliable source to consult for selecting eyepieces with the various telescope designs in mind?

    I've always been a little haphazard in that regard and it would be helpful if there were list or table showing which eyepiece designs were preferred for the various telescope types. It would be better if there were a brief explanation as to why.
    OTA's: 203mm f10 Meade SCT (LXD75); Antares 80mm Refractor w/William Optics APOGrade f6.9 objective; Orion Starseeker 80 f11.2 Refractor
    Mount/tripod's: Meade LXD-75 EQ; Orion Starseeker IV ALT/AZ; Celestron Heavy Duty ALT/AZ
    Eyepieces:Meade - 26mm plossl, 12mm Astrometric; GSO (OPT badge) 2" Superview 50mm & 30mm 1.25" 15mm; TMB Planetary Series 9mm, 6mm, & 4mm: 10mm & 23mm 60° that came with the 80mm f11.2
    Barlows: Orion 2x Shorty; Meade 4000 Series 3x

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    Default Re: Eyepiece selection by telescope type

    There are two issues that need to be addressed.

    1) What is the speed of the light cone which the eyepiece can handle.That is documented in a sticky link here:

    Sticky: Evolution of Eyepiece Design

    On page 8 there is a chart listing the eyepiece design types snd in the upper right of each pane for each type there is the f/# which is the fastest light cone that can be handled well by design.

    2) The second issue is matching the curvature of field characteristics of the telescope to that of the eyepiece. SCTs, Refractors, Newtonians all have different curvature of field characteristics. This issue is treated in books like

    Telescope Optics, A Comprehensive Manual for Amateur Astronomers by Harrie Rutten and Martin Van Venrooij

    However the member here mental4astro is reportedly working on a write up.

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    ST80 (mods for white light solar), SV ED80 f7 Newtonians: Z12 f5 Catadioptrics: VMC110L, Intes MK66 EPs: KK Fujiyama Orthoscopics, 2x Vixen NPLs (40-6mm) and BCOs, Baader Mark IV zooms, TV Panoptics, Delos, Plossl 32-8mm. Mixed brand Masuyama/Astroplans Binocular Nikon Aculon 10x50, Celestron 15x70, Baader Maxbright. Mounts: Star Seeker III, Vixen Porta II, Celestron CG5, Orion
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    Default Re: Eyepiece selection by telescope type

    Quote Originally Posted by not_Fritz_Argelander View Post
    There are two issues that need to be addressed.

    1) What is the speed of the light cone which the eyepiece can handle.That is documented in a sticky link here:

    Sticky: Evolution of Eyepiece Design

    On page 8 there is a chart listing the eyepiece design types snd in the upper right of each pane for each type there is the f/# which is the fastest light cone that can be handled well by design.

    2) The second issue is matching the curvature of field characteristics of the telescope to that of the eyepiece. SCTs, Refractors, Newtonians all have different curvature of field characteristics. This issue is treated in books like

    Telescope Optics, A Comprehensive Manual for Amateur Astronomers by Harrie Rutten and Martin Van Venrooij

    However the member here mental4astro is reportedly working on a write up.
    Thanks, I'll check those out.
    OTA's: 203mm f10 Meade SCT (LXD75); Antares 80mm Refractor w/William Optics APOGrade f6.9 objective; Orion Starseeker 80 f11.2 Refractor
    Mount/tripod's: Meade LXD-75 EQ; Orion Starseeker IV ALT/AZ; Celestron Heavy Duty ALT/AZ
    Eyepieces:Meade - 26mm plossl, 12mm Astrometric; GSO (OPT badge) 2" Superview 50mm & 30mm 1.25" 15mm; TMB Planetary Series 9mm, 6mm, & 4mm: 10mm & 23mm 60° that came with the 80mm f11.2
    Barlows: Orion 2x Shorty; Meade 4000 Series 3x

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    Default Re: Eyepiece selection by telescope type

    Referring to the table starting on page (i) I assume the Eye Relief value is a multiplier used with the Eyepiece Fl (ie E=0.8Fe). I'm a little confused where the value called out is "0".
    OTA's: 203mm f10 Meade SCT (LXD75); Antares 80mm Refractor w/William Optics APOGrade f6.9 objective; Orion Starseeker 80 f11.2 Refractor
    Mount/tripod's: Meade LXD-75 EQ; Orion Starseeker IV ALT/AZ; Celestron Heavy Duty ALT/AZ
    Eyepieces:Meade - 26mm plossl, 12mm Astrometric; GSO (OPT badge) 2" Superview 50mm & 30mm 1.25" 15mm; TMB Planetary Series 9mm, 6mm, & 4mm: 10mm & 23mm 60° that came with the 80mm f11.2
    Barlows: Orion 2x Shorty; Meade 4000 Series 3x

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    Default Re: Eyepiece selection by telescope type

    Quote Originally Posted by GulfCoastGuy View Post
    Referring to the table starting on page (i) I assume the Eye Relief value is a multiplier used with the Eyepiece Fl (ie E=0.8Fe). I'm a little confused where the value called out is "0".
    It means that the exit pupil is located at the back surface of the lens, the eye relief is 0. So no confusion, just a design that has really short eye relief!
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    ST80 (mods for white light solar), SV ED80 f7 Newtonians: Z12 f5 Catadioptrics: VMC110L, Intes MK66 EPs: KK Fujiyama Orthoscopics, 2x Vixen NPLs (40-6mm) and BCOs, Baader Mark IV zooms, TV Panoptics, Delos, Plossl 32-8mm. Mixed brand Masuyama/Astroplans Binocular Nikon Aculon 10x50, Celestron 15x70, Baader Maxbright. Mounts: Star Seeker III, Vixen Porta II, Celestron CG5, Orion
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    Default Re: Eyepiece selection by telescope type

    Clears that up, thanks.
    OTA's: 203mm f10 Meade SCT (LXD75); Antares 80mm Refractor w/William Optics APOGrade f6.9 objective; Orion Starseeker 80 f11.2 Refractor
    Mount/tripod's: Meade LXD-75 EQ; Orion Starseeker IV ALT/AZ; Celestron Heavy Duty ALT/AZ
    Eyepieces:Meade - 26mm plossl, 12mm Astrometric; GSO (OPT badge) 2" Superview 50mm & 30mm 1.25" 15mm; TMB Planetary Series 9mm, 6mm, & 4mm: 10mm & 23mm 60° that came with the 80mm f11.2
    Barlows: Orion 2x Shorty; Meade 4000 Series 3x

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    Default Re: Eyepiece selection by telescope type

    nFA sums up two main criteria nicely. However, applying it to practice is not always straight forward.

    Many manufacturers keep in dark designs of their EP lines. Also, personal preferences are hardly universal.

    For instance I seem to have higher tolerance for the field curvature, but just can't stand heavy EPs. Thus, those well corrected glass pineapples are just dead weight to me, but I am happy with EPs, which are getting bushed all over CN.

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