Learn more physics!
What lenses are found in binoculars?
Probably the most important lenses in binoculars are the convex lenses. These lenses make small (distant) objects look bigger (closer). Some binoculars also use fine concave lenses to help focus images more clearly for your eyes. Lastly, many binoculars use prisms. This isn't to make rainbows, though - instead, sets of 2 prisms for each side of the binocular lets the holes that you look through be closer together than the holes that the light comes in through. Prisms are also used if the arrangement of convex lenses in the binoculars would make the image appear to be upside down. Inserting the prisms reverses the image again, making it look right-side up.
(published on 10/22/2007)
Follow-up on this answer.