From: "Jim Miller" 
To: , 
Reply-To: "Jim Miller" 


the reason that reducing upper end mass isn't a free lunch is that it that
an eyepiece change which has a much different mass represents a greater
percentage of the secondary mass.

you can compensate of course with a variety of balancing/ballasting schemes
but it's another thing to tinker with in the dark.

you can see my weight and balance sheet at my website, www.jtmiller.com,
for my scope. i did a weight and balance estimate as i started building and
kept updating as i went along.

jtm

----- Original Message -----
From: 
To: 
Sent: Saturday, August 02, 2003 8:43 PM Subject: Re: ATM Re: Minimalist dobs.



You wrote
"Reducing the total upper end mass isn't quite as useful unless you
have som sort of variable balancing mechanism built into the mount."

You lost me here. How do you build a balanced scope if you are not taking
into acount the weight of the upper end? How are you determining where the
OTA center of mass is?

Tom
Tucsom, AZ
Date: Fri, 1 Aug 2003 11:32:07 -0400
From: "Jim Miller" 
Subject: Re: ATM Re: Minimalist dobs.

IMO, the big advantage of a lightweight secondary would be the opportunity
to dramatically reduce the suspended mass of the entire secondary
hub/mirror/cell combination and as a result reduce the size of the
suspension wires and resulting diffraction.

Reducing the total upper end mass isn't quite as useful unless you have
some sort of variable balancing mechanism built into the mount.

jtm

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