I have a Celestron 60LCM refractor telescope. It has a 60mm aperture and a 700mm focal length. It came with two eyepieces. One is 25mm and the other is 9mm. They are marked only with their focal length - there is no brand name or part number printed or stamped on either. I can view Jupiter and Saturn through both eyepieces. However, even though the 9mm should have a higher magnification, the planets actually look smaller when looking through it than they do when viewing them through the 25mm eyepiece. Is this a field of view issue? And if so, what field of view should I look for when I shop for new eyepieces for viewing Saturn and Jupiter?
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$\begingroup$ Can you post some images of these? Maybe the markings were misplaced. Sometimes we can tell the true focal length of the eyepiece just by looking at it. $\endgroup$– User123Commented Dec 20, 2020 at 21:06
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$\begingroup$ I posted an image of the eyepieces. $\endgroup$– Tom VCommented Dec 20, 2020 at 21:39
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$\begingroup$ If the planets look smaller in the 9mm than in the 25mm then it's possible that the eyepiece has as some point been disassembled and reassembled, with one of the lenses reversed. $\endgroup$– Aaron FCommented Dec 20, 2020 at 23:59
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$\begingroup$ If K is for Kellner, the flat lens surfaces should face outward. I doubt that reversing one would have much effect on magnification. $\endgroup$– Mike GCommented Dec 21, 2020 at 2:28
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1$\begingroup$ It could also be possible that one eyepiece has a much wider field of view than the other, misleading you into thinking the image is "smaller" because it doesn't fill the field of view as much. $\endgroup$– Arthur KalliokoskiCommented Dec 22, 2020 at 21:51
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