[MortonH]

Realise there's no correct answer to this question because obviously it depends on the frequency of use, exposure to moisture, etc. but am wondering in very general terms how much reflectivity might be lost over time.

Reason I'm asking is that I'm currently looking for a 10" Dob. My previous Dob was 8" so I'm looking to increase the aperture. But if I buy a used 10" Dob that's had a few years of use, am I really buying 10" of aperture? Or would a brand new 8" show just as much?

Any thoughts?

Cheers

Morton