List of lenses I have

  1. Convex - 200mm F.L - 50mm Dia
  2. Convex - 50mm F.L - 50mm Dia
  3. Convex - 40mm F.L - 40mm Dia
  4. Convex - 45mm F.L - 25mm Dia
  5. Concave - 200mm F.L - 50mm Di

I tried to make a telescope with 200mm convex as objective and 40mm convex as eyepiece. it gives 5x which is very less maginification. With other lenses I have what combination can help me improve the magnification.? is it possible to have more that two convex lens lined up to get more magnification ?

  • 2
    $\begingroup$ Would AstronomySE be a better place for this? I do appreciate the physics though, I just wonder if they have an answer there already. $\endgroup$
    – user167453
    Commented Sep 12, 2017 at 12:33
  • 1
    $\begingroup$ What is wrong with 5x particularly if the telescope is hand held? $\endgroup$
    – Farcher
    Commented Sep 12, 2017 at 13:01
  • $\begingroup$ @Farcher not enough to look at even moon or nearby planets $\endgroup$
    – Khaleel
    Commented Sep 12, 2017 at 13:26

1 Answer 1


Sure, if you put your concave lens a little in front of your one of your convex lenses, you would get an image that is much farther away than the convex lens focal length. Then with your 40 mm eyepiece, you could get more magnification. Try experimenting!

But Farcher is also right: you need to think about practicality. The more optics you put in there, the more complicated the alignment will be, and your resolution will still be ultimately limited by the numerical aperture of your 50 mm diameter lenses. 5x is okay for handheld. I'm assuming you don't want to buy a cheap binocular, for which you could get 10x no problem?

  • $\begingroup$ buying is not a problem. I want to kill my leisure with exciting experiments. thanks for your input on concave usage. will give it a try $\endgroup$
    – Khaleel
    Commented Sep 12, 2017 at 13:28
  • $\begingroup$ Great! Experimentation is always encouraged. Have fun! $\endgroup$
    – Gilbert
    Commented Sep 12, 2017 at 13:33

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