Re: 1/6 or 1/8 wave

Hi Bill:

Thanks. I'm certainly aware of the difficulty of producing a good
figure in plate glass, but I'm a bit skeptical that this will be a huge
problem with the spheres on the Intes scopes. It should also be
rmembered that the wavefront error on these scopes is the product of
all the components.

Uncle Rod

William R. Mattil wrote:
RMOLLISE wrote:
Hi:

1. That's his opinon.

Hi Rod,

While you are correct that it is his opinion it is also true that in the
course of polishing a mirror heat is generated. That heat changes the
mirrors figure slightly. So it becomes problematic to get a good surface
without altering the figure. A rather decent glass pusher once told me
that he would work a rough zone/high spot by warming that spot with his
hand prior to working it.


It should also be noted that these are not spherical, or parabolic mirrors.


2, The Deluxe scopes didn't _use_ Pyrex.

Indeed.


Regards

Bill

PS: The last time I spoke to R.R. about a large mirror he couldn't
provide a zero expansion one due to problems in getting the blanks.

.

Relevant Pages

  • Re: whereabouts of John Pumpernickel?
    ... I had the guy send me results of mirror testing first though. ... quality is not ... Had to go through 3 scopes before I had a decent mirror. ... After my uncle had his stroke, his personality completely changed. ...
    (sci.astro.amateur)
  • Re: Buying a new telescope...LONG
    ... sound advice. ... the smaller scopes you had first selected are a poor ... secondary mirror support spiders, and horrible Primary Mirror ... An 8" Dobsonian Reflector has advantages that it will be relatively ...
    (sci.astro.amateur)
  • Re: whereabouts of John Pumpernickel?
    ... I've had several offers despite the bad economy but then ... I had the guy send me results of mirror testing first though. ... They have a large variety of scopes. ... After my uncle had his stroke, his personality completely changed. ...
    (sci.astro.amateur)
  • Re: whereabouts of John Pumpernickel?
    ... I had the guy send me results of mirror testing first though. ... They have a large variety of scopes. ... scopes are Chinese imports. ... After my uncle had his stroke, his personality completely changed. ...
    (sci.astro.amateur)
  • Re: DOB Dilema
    ... > want to seek out as far as a Dob goes...yes, I can try them all at a star ... though in larger scopes even fairly ... of the 100% illumination area, ... Mirror Quality is an issue. ...
    (sci.astro.amateur)