StarStructure 24" f/3.3 | ServoCAT/Argo Navis
Astro-Physics 175EDF | AP1100GTO | ATS Portable Pier
Psalm 19.1 - A Psalm of David. "The heavens declare the glory of God, and the sky above proclaims his handiwork".
Quote:The question to ask is if there are SiO2 coatings on the mirror.Silicone Dioxide is used both to improve transmission, and to protect the aluminum from loosing reflectivity.If it does not have this kind of coating, then at some point in the future you may have a reflectivity issue, but even aluminum can last a long time in a closed tube where it is not usually exposed to weathering. There are 25 year old C8s out there that seem to be working fine.I would look for SiO2 overcoating on the primary, and for high transmission coatings on the rear of the Meniscus (MgF2, which like SiO2 seals the secondary spot and helps preserve the aluminum finish).I am sure it will be fine after only 12 years, but in time, it could be an issue and not having these coatings should not appear to be a show stopper if the coatings otherwise look good, but enhanced aluminum is far more durable and has a far better chance of holding reflectivity for a very very very long time.
Skywatcher BD 180mm f/15 Mak Intes M703 180mm f/10 Mak ED102 f/7 refractor Vixen LVW42, 22,13,8,5 and Vixen LV50