Hello, I'm in the process of upgrading my 10" dob to a 16" but having some trouble deciding on the mirror.
Im concidering two mirror, either pyrex or soda lime glass, the maker says the quality and coating will be the same on both mirrors 1/8, 93-96% and that the only difference is that pyrex handles temperature swings better.
The price is roughly 450£ extra for pyrex. The telescope will be located in my roll-off roof observatory so it will not need much of a cooldown time (if any) before using, the temperature in the observatory is only one or two degrees higher than outside temp.
Im observing from Sweden and when talking about temperature swings im not certain how to think about that. A typical night it might be -8C and over a couple of hours drop down to -10-12C, is that enough of a swing to create problems for soda lime glass?
Besides being more resistent to temp changes is the durability/lifetime of these two types about the same?
Thanks for any input