I own a tabletop Sky-Watcher Heritage 130mm tabletop Dobsonian with a f/5 130mm aperture and 630mm focal length. 25mm wide-field eyepiece and a 10mm narrow-angle eyepiece. Last night I took it out to see the crescent moon. Initially, I used the 25mm wide-field on focused on the Moon and the image came out properly with minimal blur. However, when I replaced the 25mm with the 10mm narrow-angle eyepiece, the image was really blurred, making the moon a blob. Am I doing something wrong?

  • $\begingroup$ Is this the first time you experience this issue ? $\endgroup$ Commented May 6, 2022 at 14:37
  • $\begingroup$ @KavinIshwaran I got this telescope last week, first time using the narrow-angle eyepiece. $\endgroup$
    – WarpPrime
    Commented May 6, 2022 at 14:38
  • $\begingroup$ What is focal length and what is the clear apperture of the telescope? That is: is the 10mm producing useless magnification, magnifying only the diffraction rings (which sadly is frequently found for cheaper telescopes for one of the shipped eye pieces)? $\endgroup$ Commented May 6, 2022 at 14:41
  • $\begingroup$ astronomy.stackexchange.com/questions/45230/… or astronomy.stackexchange.com/questions/20981/… might give some answer $\endgroup$ Commented May 6, 2022 at 14:45
  • $\begingroup$ This scope comes with a 650mm Focal length, I own a similar telescope, the astromaster 130eq which has the same 650mm focal length and the 10mm should be perfectly fine with observing moon. I see that this scope has no focusing knob, instead it comes with a "wheel" have you checked with the focusing wheel ? Is that adjusted in focus ? $\endgroup$ Commented May 6, 2022 at 14:46


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