Lunt Wedge

I was reading about the Lunt Herschel wedges, and at least one dealer claims they should only be used with air-spaced refractors of 150mm or less. I find this peculiar. I note that AP makes no such claim about their ultradeluxe Baader wedge. It doesn't seem likely to me that an oiled objective would get any hotter than an air-spaced one. What issues are involved here?

Hi Joe

no Issues, that dealer who post that, does not know what a wedge does.

A Herschelwedge of any manufacturer can be used in any refractor telescope with out any risc

regards
Markus