new sort glass for protective front pane

Lately the standard UV filter as protective pane in front of the lens has got as alternative chemically hardened plain, colourless or even coloured glass.

Now a new substrate comes in use that is harder in itself: glass-ceramics.

Next year Sigma shall introduce glass-ceramic protective panes mounted in filter-thread rings

Would be a Schott Glass product in conjunction with Sigma?

Mick.

The protector will be completely made in Japan with glass-ceramic from Ohara glassworks.

Optical grade glass-ceramic is already offered. Though I did not yet know of a photographic application.