oalithgow

Hello fellow SGL members and DIY´ers. I have recently built a Truss Dob with a 20” mirror acquired from Hubble Optics. The mirror came well packed and nicely coated, but I notice that the coating had a “blueish colored tint” on the aluminum coating when looked at any angles beside straight to.. I Thought this was a normal characteristic of this manufacturer coating, so I continued with the buld. After building and tested the telescope, and also comparing it against a 17” dob I also made, with an old coulter mirror…I’ve notice that in the 20”, the image showed this blue tint slightly, as if like it had a lite blue-green color filter on the eyepieces, the 17” on the other hand showed a bit better contrast (with darker background) and truer color images. The 20” had better quality optics over all, I might say, but this blue-green tint on the images its bothering me, also the light gathering looked almos the same in both the 17.5" and the 20" After contacting the manufacturer (HO Sales person) and trying to explain this issue with photos an all, at the end they said that this is normal for their Enhanced Coating. I looked for photos on the net of other similar mirrors from HO, but couldn’t recall any blueish color over the coatings. Here are some pictures of the 20” mirror to see what you mirror-coating experts think about this. Thanks for looking