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Optical DIY refractor telescope

  1. May 17, 2016 #1
    So, I recently finished my refractor telescope. I have a objective lens of 80mm and focal length of 900mm, 70mm focuser, tube length is 99.8 cm. I have a 25mm and 9mm eyepiece.

    I have been testing it out during the day time, on objects I can easily spot. First I use no eyepiece to focus on an object, then I use the 25 mm eyepiece to view the object.

    So here's the problem: Without the eyepiece and just looking through the focuser I can see objects as I should inverted and clear just like it should be. But once I put the 25 mm eyepiece, it just turns completely blurry and empty (since it's daytime it just turns bright white). So i use the focuser to try to get a clear image, but no matter what I do I cannot get an image. I have tried several different object at different distances.

    I'm just wondering if there's something I can do to fix this.
    Thanks for any advice.
  2. jcsd
  3. May 17, 2016 #2


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    Try holding the eyepiece by hand and see how far out you need to go to bring it into focus. That will tell you how much travel your focuser needs. Sounds like you have too much travel. Your tube length is 998 mm and your objective focal lenth is 900mm. So you probably need to shorten the tube to reach focus.
  4. May 18, 2016 #3
    Thanks. I will try this!
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