Re: [ATM] Book Review.... sort of

[Mike Lockwood <melockwo@uiuc.edu>]

Hi,

Jerry wrote:
> Still, I am always interested in how
> other people do it, and I haven't made a perfect edge yet.  Next time.

When do you notice the edge turning?  During figuring?

> The 3 volume ATM book while having much good information in them, also has
> much misinformation. I would say that they were largely an impediment to
> finishing my first mirror.

Agreed.  The figuring advice is widely varying and sometimes 
contradictory.

> "How to Make a Telescope" however is very good.... All of his figuring methods are
> illustrated on two pages. I've used all of them at one time or another.  My
> only complaint is that I would have liked him to have described them more
> fully. Still I have not found better anywhere. If you have, let me know.
> My opinion is that Texereau is still the best guide to mirror making.

Agreed.  With practice, I have found Texereau's techniques to be very 
effective.  There are many subtle comments that ring especially true 
after you have made many mirrors.  In developing my own techniques and 
tricks, I have found that many are similar to Texereau's.

The one thing I dislike about Texereau is the bias against fast focal 
ratios.  Granted, and F/4 primary mirror is not easy to make, but 
Texereau seems to imply that it is nearly impossible.  (Also, the very 
slow Cassegrains he promotes are very good for planetary work, but are 
good for little else.)

What is required to make faster mirrors is mastery of subdiameter lap 
work, which Texereau only briefly covers.  Of course fast mirrors 
demand more testing skill, too.

Another valuable feature of Texereau's book is his chapter on 
Cassegrain secondaries, which can be found nowhere else.  Of course 
for seriously hyperbolic secondaries, one must again develop his/her 
own techniques.

Mike Lockwood
http://bi-staff.beckman.uiuc.edu/~melockwo/index.html

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