Glass question

Would some of you lens designing and making types (Roland, especially, but also anybody else who can help) please straighten me out a bit concerning the mystery of "eco-glass"? Less toxic chemicals spread around is surely a good thing, but is the glass quality as good, and are as good achro and apo combinations of glasses available, as with old-fashioned lead, arsenic, cadmium, etc. compounds? How prevalent is the use of eco-glass in modern consumer optics? Should the "conniseur" demand toxic substances?
Thanks,
Ron

A lot of the old glass types contained lead and arsenic among other bad substances. This exposed the workers at the glass plants to these toxic substances. It also fouled the air around glass plants to some degree because the pouring of hot glass released fumes into the air and contaminated neighborhoods in the vicinity of the plant.

The new glass types have identical optical characteristics to the old. Some glasses have been dropped altogther, but these were not generally used in amateur optics anyway.

The main concern for us lens makers has always been the internal quality of the glass, which can vary from excellent to really poor, depending on how the glass is poured, cut, annealed, etc. This has always been the case, old glass or new eco-friendly glass. Glass companies do not guarantee their quality in the price range that amateurs wish to pay, so it is sometimes a total gamble for the lens manufacturer. It is possible to get an entire batch of excellent glass, or conversely it is possible to get hundreds of blanks that are so bad, they are unuseable. It is up to the lens maker to throw them away, eat the loss and go on, or make lenses out of them and hope nobody notices the astigmatism, coma and other defects that arise from that poor glass.

There is unfortunately no way around at the present cost structure of amateur optics. To get guaranteed quality in each blank will cost more than the entire telescope is worth in some cases.

Rolando