RE: ATM - a 'scope for the classroom

["James O'Malley" <omalleyj@eclipse.net>]

On Wed, 4 Aug 1999, Bertapelle, Ken wrote:

> 
> > 
> > -----Original Message-----
> > From: Adam Perkins [mailto:scopeguru@yahoo.com]
> > Sent: Wednesday, August 04, 1999 10:53 AM
> > To: atm@shore.net
> > Subject: ATM - a 'scope for the classroom
> > 
> > Hey,
> > 
> > I've decided to build a scope for my wife's Sixth-Grade students.  She
> > and I figured that they could borrow it for a week or two at a time,
> > and get some fun out of it.
> ><snip>
> > - a long (f/8-10) focal ratio for good performance with cheapo
> > eyepieces and poor collimation
> 
> This jumped right out at me.  I'd avoid thinking about accepting poor
> collimation right from the start.  According to Suiter, it has a very
> big negative effect on the image.  Instead think about how the kids 
> will learn to collimate the scope properly.
> 
> - KenB
>
My oldest daughter is entering 6th grade this year, she is a bright and
patient kid, but I think collimation would be frustrating for her. I would
suggest instead making it very difficult to lose collimation:
rigid overall construction: sonotube wrapped in fiberglass?
thicker than usual spider vanes 1/16" steel
push-pull screws with torx heads for primary and secondary collimation
over-length tube to keep fingers off the secondary
unit power finder

Make it with nothing to adjust but the focuser, and able to withstand
being tossed in a car trunk. Then give it a quick checkup and tweak the
collimation between loans. Also I would suggest not making too high
magnification available, say 80x. And keep the mount actions a little on
the stiff side, I love being able to barely touch my tube at high power,
but my daughters knock objects out of the FOV by bumping the focuser with
their nose, or reflexively laying their hand on the tube.

good luck, this is a noble objective
jim

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Jim O'Malley    |
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