Included in this educational lens set are the lenses you need to quickly and easily show the difference between a Galilean and a Keplerian telescope, and more.
We included a large diameter lens to be used for the objective, 60mm diameter, with a relatively short focal length of 300mm, our item #L14909. That way it will be easy to use the lenses to show the difference by hand holding (and you can put them in a pair of sliding cardboard or plastic tubes if you want).. The large objective will gather more light than the much smaller ones traditionally used for this purpose.
For the Galilean scope you use the included 38mm diameter by -50mm focal length double concave lens for the eyepiece, our item #L1951D. This will give you a power of 6X with an erect image but with a very small field of view and a somewhat distorted image.
For the Keplerian scope you use for the eyepiece, the included 50mm diameter by 50mm focal length double convex lens, our item #L1901D. This will give you the same power but the image will be upside down and the field of view will be much larger than the Galilean scope and a clearer image.
We chose the L1951D and the L1901D because their focal lengths negate each other when you put the two lenses together. You get just a window! Should be interesting to students.
