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  1. #1
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    Default 25mm eyepiece is just a tad too wide to fit...



    I searched first...obviously I'm afraid of asking a really obvious question, but now it's bugging me.

    I have a 25mm eyepiece that appears to be 1.25", and yet apparently it's a bit closer to 1.26 or 1.27. It's just a fraction of a millimeter too wide to fit my telescope or my barlow. And no, it's not the 2-inch format; I really think that just shaving off a tiny bit around the edges would have it fitting without a problem.

    Now mind you, it is kind of a cheapie, and it was probably even one of the ones thrown in with the scope in the first place when it was new. It has no brand name marked, the outer barrel is plastic, and all that's written is its focal length. But really, even with a cheap eyepiece, is it really that hard to make one that fits? The only thing I can think of is conversions...in France, 1.25" becomes 31.75 mm. But sometimes, eyepieces online are (incorrectly) listed as 32mm. That, to me, would account for the small discrepancy. Is it just a matter of sloppy number-rounding, or is there something else afoot here? Or do they actually make 32mm telescopes, in addition to 31.75's? Sounds unlikely to me...which is why I'm asking here! Note that my 7 and 10mm eyepieces fit without a problem, it's just the 25mm.

    Thoughts?
    10" Skywatcher dobsonian reflector, 70° 26mm (Q70), 52° 25mm and 10mm, 82° 7mm, 2x barlow

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    Default Re: 25mm eyepiece is just a tad too wide to fit...

    I want to say it is a manufacturing flaw. I have one or two eyepieces that are snug fits. But I have never heard of a 1.25 simply being too big
    Nexstar SE8 mount with Farstar C8 OTA (Caroline) Meade Series 5000 HD-60 25mm Paradigm Dual ED 25mm 18mm 15mm, Baader 21mm 17mm plus tunning rings, X-Cel LX 2X Barlow, various other bits and bob.

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    Default Re: 25mm eyepiece is just a tad too wide to fit...

    Sounds like that 2" diagonal for $25 that I had to grind down with the belt sander to make it fit. I recommend doing the same if you have a belt sander because it is much easier than the hassle of sending it back. After I reported this issue with the vendor he sent me a new one quickly that fit.
    ... Henk. Telescopes: 6" Mak-Newt (Comet Hunter), ES ED127CF, ES ED80, Zhumell Z12, Coulter Odyssey 10, AT6RC, Venture RX-7, Celestron Skymaster 20x80, Mounts and tripod: Losmandy G11S, AVX, LXD55, Tiltall, Cameras: Fuji X-a1, Canon SX40, Xt, XSi, T6, ELPH 100HS, DIY: Dob and camera barndoor trackers, afocal adapter, Dob with foldable base and Az/Alt setting circles, Accessories: SSAG, Plossls, Barlows, Telrad, laser collimators (Seben LK1, Z12, Howie Glatter), Cheshire, 2 Orion RACIs 8x50, Software: DSS, ImageMagick, PHD, Nebulosity, Photo Gallery, Gimp, CHDK

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  4. #4
    NBertrand's Avatar
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    Default Re: 25mm eyepiece is just a tad too wide to fit...

    Thanks--yes, normally I'd do that, but sending it back is not an option because not only did I obtain everything secondhand, but I have no idea who to return it to. No brand name, no accountability, I guess.
    ...and I don't have a belt sander.

    It still works and all, mind you; I just have to manually hold it against the focuser in order to see things.

    It's not a huge deal. Looks like the concensus is on manufacturing error...eventually I might get a nice wide-field low power piece anyway.

    Thanks for the replies.
    -Me
    10" Skywatcher dobsonian reflector, 70° 26mm (Q70), 52° 25mm and 10mm, 82° 7mm, 2x barlow

  5. #5
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    Default

    I had a similar problem with a 2" 56mm plossl that I recently purchased. I ended up sanding down the barrel to make it fit: Reducing barrel diameter?

 

 

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