Question:
Mr. Knoppow's reference in my original posting as to lens
construction to the common use of plastics as eye glass lenses
raises an intriguing guestion. Indeed, if plastics are suitable
for eye glases, why are plastics not suitable for photogarphic
lenses given that no film can record all the detail and color
nuances that the human eye/brain can record?
The favor of comments on this secqual to my original posting on
this theme of why are plastic materials not used for lenses will
be greatly appreicated.
Answer:
I might argue that my annual trip to the eye glasses store is anything but
cheap, however that's not the point.
With plastic eye glass lenses a set lasts me about six months before
scratches begin to annoy me. So I by two pair. When I was younger, and took
less good care of my glasses, but my glasses were glass, I usually got
through a full year.
Why plastic on eye glasses? Weight. Most people want as little weight on
their nose as possible and plastic is lighter than glass. Polycarb is even
lighter than standard plastic. Weight, especially as the strength of the
lens increases, matters.
Safety, good polycarb lenses are less likely to shatter when struck than
glass.
Someone also mentioned that thick lenses of plastic have problems because of
the large molecule size. Eye glasses as a whole have equal or less thickness
than many single elements let alone 4 or more elements.
