Re: 1/6 or 1/8 wave
- From: "M104galaxy@xxxxxxxxx" <M104galaxy@xxxxxxxxx>
- Date: 26 Jan 2007 16:50:02 -0800
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
.
- References:
- 1/6 or 1/8 wave
- From: khobar
- Re: 1/6 or 1/8 wave
- From: Melweaver
- 1/6 or 1/8 wave
- Prev by Date: Question about magnification -- binos and film camera
- Next by Date: New group...real.amateurastronomy
- Previous by thread: Re: 1/6 or 1/8 wave
- Next by thread: Uncle Rod's Used CAT Buyer's Guide 7th Edition Now Available (free)!
- Index(es):
Relevant Pages
|
Loading
