Keplerian telescope

A keplarian telescope?

A keplerian telescope is a very basic way of a telescope. It consists of two convex lenses and will create a upside down image. You will find more details in the wikipedia section here: Keplerian telescope  and a technical description on how the lenses are aranged and what purpose they serve -->Refracting telescope designs<--

With (D)SLR Lenses?

• Fotographic lenses are usually very well corrected against lens errors, when compared with a single convex lens

• The magnification factor of this telescope is the ratio of the focal lengths:
  Magnification= Objective Focal lenght/eye piece focal lengh.
  Example: 200mm/24mm = ~8 times magnification

• The lens with the smaller focal length is your eyepiece. 

• This will not work with all DSLR-Lenses:

  • you need fast lenses, otherwise you will get a very small visible circle

  • Working/tried examples: 

    • Objective lens:

      • 200mm

      • 500mm

      • I recommend any lens, but bear in mind that it should be fast and have a high focal lenght

    • eyepiece lens:

      • 50mm (nifty fifty)

      • 24mm (pancace)

      • I recommend a compact prime lens

  • The lens that serves as a eye piece needs to be compact enough that the focal point is sufficiently accessible for your eye. You obviously cannot put your eye inside your lens.
    Lenses that probably do not make any sense to try:

    • Kit-Lenses or superzooms as an eyepiece as the lens usually is longer than the focal length

When to print

• You inherited some old lenses?

• You borrowed some lenses?

• You are curious what this keplarian telescope could be?

• You have time on hand?

• You want to extend the "reach" for your smartphone?

How to print

With painted supports for the bayonet mount faces. Use the fill option:

Use a dark filament!

How to use

• Focus both lens to infinity

• Hold the eyepiece to your eye to check the capabilities

• Align your smartphone camera to the telescope and check necessary settings

• Mount your Smartphone 

• Rotate the image in postprocessing