Quote:

---

Quote:

---

What is that strange radial spider pattern on the 2004 c11? I have seen this on one other c11...

---

And whose C11 might that be ?

Yeah I figured it out last week when I was looking at pictures of a disassembled C14 and noticed the ribs on the back of the mirror. Also, as the mirror cools, those ribs will probably show themselves as well. I notice in my C11 they're much less visible but still there and fairly easy to see even after the scope has stabilized thermally . I catch a very faint hint of them in the C14 as well but I never would have gone looking if I had not seen the photo of the back of the C14 mirror.

Jeff

---

From what I've read, it's nothing to do with the primary but an imprint into the corrector's figure from the grooves in the master block used to facilitate the vacuum. Apparently Celestron later changed their master blocks to avoid this problem. Used to be fairly common, even seen in-focus, in the older Celestrons. Newer Celestrons don't have it.

Tanveer.

Post Extras: