[ATM] Plastic Lenses (POLYCARBONATE)

[Nils Olof Carlin]

>
> 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.

What surprises me is the negative attitude to plastic lenses - the 
ones I wear daily have a coating (or several?) including antireflective 
that is second to none I've seen on glass, scratch-resistant (no 
obvious scratches since perhaps 5 years - as opposed to my first glass 
lenses, but that may be coincidence), and also water-resistant - water 
will run off and I usually don't even have droplets to remove (a 
feature I've never seen on glass!). 
This of course does not mean that it would be practical or economic to 
make telescope optics from such material, but good quality coated 
optical plastic fantastic hardly deserves the putdown it has had here. 
But the manufacturing techniques may need to be very different.

Nils Olof