Posted By Jim Moscheck
Last Spring when I heard that there could be problems with getting Pyrex I decided it was now or never so I ordered a premium primary mirror and a Pyrex secondary from Protostar for my first homebuilt truss dob. Well, the primary mirror is taking about 6 months longer than promised due to problems obtaining new blanks, but I've been told it has finally been started and I should receive it soon. Interestingly, I was on Protostars website today where is says that as of November they are discontinuing Pyrex diagonals and now only offering Quartz. My secondary was also received later than originally promised and I guess I got one from the last few batches.
Is Pyrex really dead and what will replace it for Newtonian telescopes?