[ATM] Plastic Lenses (POLYCARBONATE)

[Dominic-Luc Webb]

On Wed, 1 Aug 2007, Richard wrote:

> Hi Jarvis,
>
> Wednesday, August 1, 2007, 3:20:17 AM, you wrote:
>
> JK> I also use glass lens for my eyeglasses
> JK> because they are superior to polycarbonate
>
> I'm afraid your eye's are fooling you because they simply are
> not good enough to tell the difference. Glass spectacles have much
> better scratch resistance. Plastic spectacles are lighter. Optically,
> whatever they are made from, they are only made to the nearest 1/8th
> dioptre anyway.
>
> --
>
> Best regards,
>   Richard in the UK


Along these lines, I was kind of curious what the original poster
wanted to do. It is not clear to me he should dismiss plastic for
his application, if he has a specific one he wishes to share with
us. In some photometric systems, detectors cannot tell the
difference between glass and plastic filters to any significance
for the application. Of course, these a powerless flats, not lenses.

The above postings left me asking questions like, what aspect of
glass eyeglasses is superior? I thus far do not wear glasses, but I
recall a co-worker claiming an unexpected preference for one
over the other because of the extreme thickness of his prescription.
If I remember correctly, he wanted plastic due to the lower weight,
but got (required???) glass, and he had a sound reason for this. He
is on vacation, but I can ask when he returns. Maybe someone here
who knows optometry knows about some distinction in the special case
of thick prescriptions?

Dominic