[ATM] Diagonal Size

[Polaraligned <polaraligned@optonline.net>]

> Message: 1
> Date: Sun, 11 Dec 2005 22:35:46 -0600
> From: Scott Carson <scottcarson@austin.rr.com>
> Subject: Re: [ATM] Diagonal Size
> To: ntent <ntent@pctcnet.net>
> Cc: ATM <atm@atmlist.net>
> Message-ID: <439CFE22.7090200@austin.rr.com>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
> 
> i found the following article helpful...
> 
> http://legault.club.fr/obstruction.html
> 

This follows along the article by optical engineer William Zmek,
who wrote a great article in the July '93 S&T magazine on the 
effects of central obstruction.  The bottom line was that a scope
with a CO would perform as well as an unobstructed scope of
a diameter equal to the telescopes diameter minus the diameter
of the CO.  This rings quite powerful when so many go to great
legnths to avoid a CO at all costs.  If you want an 8" unobstructed,
just build a 10" standard Newtonian and it will perform as well or
better than the 8".  Chances are, it will also be smaller.  
The differences people see looking through an unobstructed scope
in many cases are just a psychological phenomenom.  "I know there
is no obstruction, therefore I am seeing finer detail".  
The biggest keys to high resolution is great optics, great collimation,
and great seeing.

Scott


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