Help with lenses for hand-made telescope

  • #1
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Main Question or Discussion Point

I'm trying to make a handmade telescope, but I'm stuck with the lenses I bought 2 lenses. they are the same
"convex from one side and concave from the other side" like glasses lenses.

then I knew that I need a double convex for both the object lens and the eyepiece lens.
so I decided to put the 2 lenses that I bought together to make a double convex lens so now air is in between the two lenses.

Is what I did going to give me a double convex lens?!
 

Answers and Replies

  • #2
BvU
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Hello Mohab, :welcome:

I'm afraid not. Unless you fill up the hollow space in beteen with glass too ...
Did you check if the two lenses have positive or negative focal distance ? (positive: they work as a magnifying glass, negative: things look smaller but stay upright).
 
  • #3
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Thanks for your reply BvU,

I've looked up to the moon with it, the moon appeared smaller, I think it has a negative focal distance.
 
  • #4
Andy Resnick
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I'm trying to make a handmade telescope, but I'm stuck with the lenses I bought 2 lenses. they are the same
"convex from one side and concave from the other side" like glasses lenses.

then I knew that I need a double convex for both the object lens and the eyepiece lens.
so I decided to put the 2 lenses that I bought together to make a double convex lens so now air is in between the two lenses.

Is what I did going to give me a double convex lens?!
meniscus lenses are fine to use; just be aware that the orientation does impact the total amount of aberrations.

What are the focal lengths of the lenses?
 

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