I would like to make a cheap zoom lens. I would like it to zoom in the
range of 8X to 80X. 10x to 80x is good too. I don't care if it has
chromatic abberation. I don't want high quality, just low cost. I
think it would consist of 3 convex lenses. $3 for each part of the
answer.

1) What would the focal length of these lenses need to be? ($3)
2) How do these lenses need to move? ($3)
3) What is the formula for 1 and 2? ($3)
4) How can I implement this movement (casing, threaded pipe, etc)? ($3)
5) Where can I buy these lenses and casing? Hopefully for a total under $20. ($3)
6) Where would I put a reticle in this confiuration? ($3)
7) How could I implement a compass reticle? ($3)

$4 bonus if all 7 are answered!

Thanks.

HI,
GA Answers are all or nothing.  If you are willing to pay for an
answer to each question, then post seven $ 3 questions and cancel this
one.  I know, that will cost you 50 cents per question, but you will
much more likely to get some of the answers you want. I would include
your explanation with each question.

http://www.schneider-kreuznach.com/knowhow/zoom_e.htm
http://www.answers.com/topic/zoom-lens

See FAQs below.

Personally, I am very doubtful that you will be able to coordinate the
movement of the lenses or construct a zoom lens with 10x to 80x
magnification.
But don't let discourage you.  :)

I'll consider the question answered in full ($25) if 1, 2, 3 and 6 are
answered. If 4, 5 and 7 are answered as well, I'll add a $5 tip.