On Aug 25, 2005, at 5:15 AM, Chris Stoddart wrote:
They don't need to have a curve on them to act as a lens. If a light
ray is hitting them at an angle, it will be deflected by refraction.
http://www.ps.missouri.edu/rickspage/refract/refraction.html
Would make all the difference between a sharp and soft image.
Yesssss, I do happen know a smidge about refraction(*). But tell me
about
those filters everyone puts in front of their lenses... or do they
not
have the same effect? :-) Is it only at the rear of the lens you
reckon
it makes a difference?
Yes, they do have an effect ... which is why I never use a filter
unless it is essential to filtering light. Anything at the rear
element of a lens, however, makes a bigger impact on the output than
at the front element. A small crack or bit of dirt on the front of a
lens is usually almost impossible to distinguish, but at the rear of
a lens it can make the lens unusable.
Godfrey
