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    Anticharmquark's Avatar
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    Default If you could only...



    I'm sure this question, or a variation, has been posed a hundred times before, but I'm truly and sincerely bo-o-o-o-ored at work right now, so let's see what you guys have to say!

    If you could only use three magnifications, what are they, and why? (This is also sort of secret research for long term eyepiece collection upgrades, but don't tell anyone)

    If I had to pick now, from my collection/limited experience, I'd say:
    50x, for wide field, deep sky, finder-type purposes and large objects
    138x for higher magnification identification and detail purposes
    208x for tougher double stars, planets, and the moon (And certain DSOs).
    ~David, Astrophysics major/wannabe~
    Telescope(s): Zhumell Z10 10" Dobsonian
    Finder(s): 8x50 RACI, Telrad
    Eyepieces: GSO 30 mm and 9 mm Plossl, ES 25mm, Olivon 6mm Planetary, Zhumell 2x barlow

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    Default Re: If you could only...

    With the focal length of my scope and how/what I most like to observe, I'd go with 84x, 138x, and 173x.

    One Power to rule them all,
    One Power to find them,
    One Power to bring them all
    And in the Darkness bind them.

    Bryan

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    :
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    f/5; Celestron C6-R f/8; ES AR127 f/6.4; ES AR127 f/9.4; Stellarvue SV102T f/7; ES AR102 f/9.8;
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    MC90 f/13.3;
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    ST80A f/5; Celestron Premium 80 f/11.4; Celestron C80 f/11.4; Unitron Model 142 f/16; Meade NG60 f/10
    Mounts: Celestron AVX; Bresser EXOS-2; ES Twilight I; ES Twilight II; iOptron Cube-G; AZ3/wood tripod; Vixen
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    Eyepieces: GSO Super Plössl 40mm, 32mm, 15mm, 9mm; ES 82° Series; GSO Superview 30mm; Celestron Plössl 26mm, 20mm; ES 70° 25mm; ES Plössl 25mm; Vite Aspheric 23mm, 10mm, 4mm; Orion Expanse 20mm, 9mm; KK Ortho 18mm, 12.5mm; Bresser 70° 15mm; Coulter Optical 12.5mm; BCO 10mm; ES 62° 9mm; Zhumell Z Series 5mm
    Binoculars: Pentax PCF WP II 10×50, Bresser Corvette 10×50, Bresser Hunter 16×50 and 8×40, Garrett
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    12×60 LW, Gordon 10×50, Apogee 20×100

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    Galaxy Hunter's Creed - When you play whack-a-mole, sometimes you hit 'em on the head, sometimes you miss 'em. But its always fun to play, and if you don't play, you ain't gettin no moles! - KT4HX

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    Default Re: If you could only...

    Quote Originally Posted by bladekeeper View Post
    With the focal length of my scope and how/what I most like to observe, I'd go with 84x, 138x, and 173x.

    One Power to rule them all,
    One Power to find them,
    One Power to bring them all
    And in the Darkness bind them.

    I think the elven kings under the sky would benefit a lot more from these powers, than say, the dwarf lords in their halls of stone.
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    ~David, Astrophysics major/wannabe~
    Telescope(s): Zhumell Z10 10" Dobsonian
    Finder(s): 8x50 RACI, Telrad
    Eyepieces: GSO 30 mm and 9 mm Plossl, ES 25mm, Olivon 6mm Planetary, Zhumell 2x barlow

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    Default Re: If you could only...

    For my uses with my Obsession I use mostly three EP's. 31mm Nagler T5 for wide field and extended objects it gives me a 1° FOV @ 82X. The 17mm Nagler T4 for 150X and is perfect for globular clusters and many galaxies, and nebula that are not extended and planets. The 12mm Nagler T4 for getting really tight on globulars and smaller galaxies, and planets @ 210X. My 4th most used EP is the 8mm Ethos for very faint small galaxies and small planetary nebula, planets @ 317X.
    JJ
    Telescopes: Assorted brands and designs from 60mm up to 203mm (9). Eyepieces: Two 6mm BO's (Brown Organics - Eye Balls). Mounts: Celestron, Meade, Orion, Vixen, Skywatcher. Cameras: Canons, Logitech, Orion, QHYs.

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    helicon64's Avatar
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    Default Re: If you could only...

    Right now I use 45x the most, 135x for zeroing in on DSO's and something in between with the ES 18mm that I bought earlier this month and have yet to try out. To catch the starlight of myriads of stars is the best thing out of these pieces of glass and metal.
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    Michael
    Obsession 18" f/4.2, Zhumell Z10 f/4.9, ES AR 152 refractor f/6.5, Celestron Skymaster 15x70's , Bushnell 10x50's
    9x50mm RACI finder, Telrad, Rigel Quickfinder, 30mm Erfle, 9mm Plossl, and full line of ES eyepieces
    Imagination is more important than knowledge. Knowledge is Limited. Imagination Circles the World... A. Einstein


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    Default Re: If you could only...

    Just got my three new "babies" in the mail today, a 31T5, 13mm Ethos and 8mm Ethos. Many years ago, I had this exact set and foolishly sold them with the 12" dob I sold when I moved to refractors. For my C6R, this comes out to:

    31T5 - 39x, 2.12* TFOV, 3.9mm Exit Pupil
    13E - 92x, 1.08* TFOV, 1.6mm Exit Pupil
    8E - 150x, 0.67* TFOV, 1.0mm Exit Pupil

    Of course I'm cheating a bit as I still have my full set of Tak Abbes for lunar, solar and planetary observing. But for DSO's I don't need anymore than those three eyepieces above.

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    Default Re: If you could only...

    I don't go by power. I go by exit pupil. So in terms of exit pupils:

    A 5-6mm because anything more is a waste of aperture.
    A 2mm since that is the maximum resolution.
    A 1mm for those really fine nights.
    An 0.5mm for when it's just crazy time.

    Now if you have 6 scopes with different f ratios that translates into a max of 24 eyepieces with different magnifications. The perfect justification for the ep addict.
    KT4HX, pikaia, helicon64 and 6 others like this.

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    Default Re: If you could only...

    Quote Originally Posted by not_Fritz_Argelander View Post
    I don't go by power. I go by exit pupil.
    Well nFA you surprised me, I thought I was all alone in doing that!
    Refractors: Antares 105 f/15, Celestron 150 f/8, Stellarvue NHNG 80 f/6.9, TAL 100RS f/10, TS 102 f/11, UR 70 f/10, Vixen SD115s f/7.7
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    Amici prism, 2" Stellarvue Dielectric, 2" TeleVue Everbrite
    Eyepieces: A-Z

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    The weakest link in the optical chain is the large nut located directly behind the
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    / camera. - Gabrielle

    Ya gotta keep this Apo/
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    thing in some balance of perspective. Apos are awesome, but long focus Achros aren't that far behind them - Siriusandthepup (CN)

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    Default Re: If you could only...

    Hi !
    A little math !
    If you call F the focal length of your scope, f the focal length of your eyepiece, G the magnification, D the aperture diameter of your scope, d the exit pupil and O the ratio F/D, you may write (F, D, f,d in mm):
    G = F/f, or G=D/d, so :
    the minimum magnification with the maximum exit pupil (6mm , or 7 mm if you are young and 5 if older) is Gmin = D/6 and Gmin=F/f1, and that gives f1 = 6 F/D or f1 = 6 • O (or 7 O if younger …) ;
    the maximum magnification is 2 D (if D in mm) and Gmax =2D = F/f2, so f2 = F/(2D) or f2 = 0.5 • O.
    Note that if you have a very good seeing and scope, the maximum magnification is 2.5 D, so f2 = 0.4 • O.
    Example you have a scope like a Zhumell Z10 10" Dobsonian : D = 10" = 254 mm, F = 1250 mm and O = 4.92 ; the minimum magnification is obtained with f1 = 6 • 4.92 ≈ 30 mm (G = 42) and the maximum magnification is obtained with f2 = 0.5 • 4.92 ≈ 2.5 mm (G = 500).
    In your case (which is mine with a 12" Dobson, and O = 4.92 ), I would have a 30 mm EP, a 24 mm one, a 10 mm one and a good 2x barlow (my choice is 31 mm, 8 mm and a barlow ; I'm waiting for a 24 mm )
    Hope this helps (if not too boring) !
    Have a good day/night !
    Arsène
    Petzval quadruplet 152/760 — XX12
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    Default Re: If you could only...

    Vintage ATCO refractor @1200mmfl- 32mm-18mm-8mm-6mm-5mm


    Meade and Celestron SCT @ 1600mmfl & 2500mmfl- 65mm-18mm-14mm-8mm


    If I could only have 3? 32mm 18mm 8mm
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    My eyes
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    1984 Meade 2120 10" SCT- 1998 U.S.A. made Celestron C8 SCT -StellarVue SV80ED Doublet- 1960's Homemade 6" F5.6 Newt - Astro Tech AT8IN Imaging Newt- Vintage 1961 H.O.C. made ATCO 80mm/1200mm refractor w/ original vintage eyepieces - 20x70
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