"The White Zone is for loading or unloading of passengers only. No Astrophotography." Cosmic Acres! Greatest restoration challenge: Tulley and Sons 3" achromat on Altazimuth mount, circa ~late 1820s
Quote:The original coating looks pretty good in the above pic. The mirror was still pretty clean, as I'd cleaned it within the last several months.
However, this is what it looked like backlit!
Quote:I certainly agree it makes life easier for a coating house and this is also in the best interest of the customer (my opinion). Gravity is not your friend in this instance.Vacuum deposition take place with an emission source stationed below the parts being coated. Depending on the size of the vacuum chamber several mirrors can be coated at the same time. A planetary system is often used. Each part rotates on axis while rotation on a central axis is conducted. To minimize shadowing of all these spinning parts clips are utilized. This keeps the cost down to do one run and coat several.If a customer has a requirement of a no non coated surface, certainly that can be provided.The other benefit much like in a mirror cell is; this reduces stress by not clamping the part tightly on the sides or being placed in a housing.Some application such as AR coatings(MgF2)takes place at pretty high chamber temps. you want to allow for CTE.Or, we're just lazy! I should mention that these statements are not implied as to why other coating houses use clips. I'm not employed at O.W.L..Bill
(snip)There are a number of knobs in that picture. Some I made out of teak and threaded rod.(snip)
Orion XT8i Sears 6333 Refractor Tasco 7TE
Celestron Sky Master 15x70 Binos Orion Sirius 10mm 25mm 32mm UO 7mm HD Ortho Expanse and Agena Astro EWAs 6mm 9mm 15mm Siebert 6.9, 9.9mm StarSplitter (SS) ES 4.7, 6.7 and 11mm 82° N2 Meade 20mm QX70
Quote:I decided to bump this thread up, since I think Lew's talked me into bringing the 8" up to CSPAMP VI next weekend!So, I've got to put a guidescope and or finder back on the thing!Maybe a 3" f/6 Jaegers with luan mahogany tube? -Tim.
Inventor of the Herschel Wedgie. Watch your back.
Astronomy - The World's Second-Oldest Profession.
"You don't know Swift from Astrola." -C.H.-