From: J Killea 
To: atm{at}shore.net
Reply-To: J Killea 


Rank beginner:

1.  I overdid it and put a 1/4" bevel on my 8" blank (I misread
some instructions).  Will this
have a material impact on my resolution and contrast?  Simple math tells me
I could achieve 98% of
diffraction-limited resolution of a similar mirror having a 1/8"
bevel.  But what is the effect on
contrast, and is any of this really going to be noticeable?

2.  I begun grinding a sagitta into this side of the blank and it stands at
about .034" max depth
(my goal is an f/6 mirror).  Is this a shallow enough curve that I can stop
grinding that side,
use it as the mirror's back side, and instead grind the other side on which
I only put a 1/8"
bevel?

3.  TDE is everyone's nightmare apparently, but isn't a bevel an extreme
example of TDE - so is
it necessary to grind the curve out to the extreme edge?  If not, how much
of the bevel can I
reasonably expect to use up by the time I'm done (8" Pyrex blank,  f/6)?

TIA!!


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