Re: 1/6 or 1/8 wave

On Jan 26, 6:50 pm, "M104gal...@xxxxxxxxx" <M104gal...@xxxxxxxxx>
wrote:
Carl Zambuto is adament that this is wrong. He claims to figure Pyrex
mirrors of over 20" with Strehl's in the high 90ties that will hold
their figures all night. And these are thin ( less than 2" ) mirrors.

Zambuto wouldn't try to mislead anyone would he??

Starmaster Telescopes ( which makes the same claims for large Zambuto
Pyrex mirrors ) would not try to mislead anyone, would they??

Do we need to call in the "Country lawyer"??

On Jan 26, 3:17 pm, midnightmadn...@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

(Melweaver) wrote:
A few more notes:

The homogeneity properties of AstroSitall and soda-lime window glass
is very good in comparison to Pyrex. Paul said he tested all three
glasses for transmission and Pyrex is not usable. This is an easy way
to determine the homogeneity of any glass.

BTW Just in handling a Pyrex mirror and putting it into a test stand,
you can see the distortion caused from the warmth of your hands. The
distortion will disappear as the temperature stabilizes after a few
minutes.

The statement about Pyrex "keeping" a figure has to do with
the stria in the glass which warps (astigmatism) the mirror as the
temperature goes down and therefore a loss of figure. For example a
70 degree mirror works fine but at 40 degrees could have 1/2 wave of
astigmatism.
---------------------------
Posted viahttp://www.AstroForum.it

--
Posted via a free Usenet account fromhttp://www.teranews.com

There is a new telescope on the market for RCOS to sue. They have the
audacity to claim their design is superior to the "classical RC"!

http://www.planewaveinstruments.com/index.php?option=com_content&task=view&id=5&Itemid=9

.

Relevant Pages

  • Re: 1/6 or 1/8 wave
    ... Carl Zambuto is adament that this is wrong. ... He claims to figure Pyrex ... And these are thin mirrors. ... The homogeneity properties of AstroSitall and soda-lime window glass ...
    (sci.astro.amateur)
  • Re: 1/6 or 1/8 wave
    ... And these are thin mirrors. ... Pyrex mirrors) would not try to mislead anyone, ... distortion will disappear as the temperature stabilizes after a few ... the stria in the glass which warps (astigmatism) the mirror as the ...
    (sci.astro.amateur)
  • Re: BK-7 Vs Pyrex---help!
    ... >BK-7 glass for their primary mirrors. ... I've just read Discovery hand tunes the mirrors ... BK-7 has lower thermal properties than Pyrex. ... The cost of the two is similar with BK7 being ...
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  • Re: 1/6 or 1/8 wave
    ... And these are thin mirrors. ... Pyrex mirrors) would not try to mislead anyone, ... top two technical guys at Celestron. ... scope at Polaris you violate Meade patents ...
    (sci.astro.amateur)
  • Re: 1/6 or 1/8 wave
    ... And these are thin mirrors. ... Pyrex mirrors) would not try to mislead anyone, ... audacity to claim their design is superior to the "classical RC"! ... The 'new scope' here, looks to be a Dall-Kirkham, with a field flattener. ...
    (sci.astro.amateur)
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