Re: ATM 24.5 inch binoculars or?(long)

["Clive Milne" <milnecd@wantree.com.au>]

Andy wrote.....
> One minor down side to
>binos is that collimation problems make it difficult to use at high power


.... Andy raises a significant point for those contemplating  bino's....
Bino's are not inherintly flawed in concept unless the designer 
chooses it to be so. If high powers are to be routine, it is necessary
to be able to easily effect collimation and adjust for parallelism at the 
eyepiece.  This is not an especially hard thing to do... it's like any 
system that has errors, ( no matter how minute )  if the deviation from 
the desired position is readily quantifiable, all you need is a means
of applying an appropriate corrective action to restore the system to
the desired position. Anyone who has figure a mirror will intuitively 
understand this..... 
     Unless you are brave...( or very, very skilled,) ..it is also wise to
give yourself as many independant adjustments as you have 
independent variables..... ( Read that again slowly, it's a significant
point )... In binoculars, this more often than not manifests itself when
the designer chooses to rely on collimation to effect the adjustment
of parallism between the two optical assemblies....  Spare yourself
some pain and frustration and give yourself the ability to tweak this 
factor independantly of collimation.
     Binocular vision has a very pleasing aesthetic quality that makes
it worth persuing, certainly the universe will become more real to you 
in the eyepiece...Binocular telescopes definately deserve more 
attention from ATM's,  I would just caution the beginners on the list 
that there are a few non trivial issues that need to be addressed to
make bino's work well.... Not terribly difficult to overcome if you tackle
them in the design stage, but significant issues none the less.
    Have fun.... 
        Clive....