Newtonian Reflector Telescope

Email: sixmhz@yahoo.com
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Introduction

I needed to find a use for the HUGE $400 tripod that I found in the dumper over on Stanford campus.

Optics

The Newtonian reflector telescope is practically the simplest telescope there is. It is comprised of only two mirrors and an eyepiece. The primary mirror (big one) is a concave mirror that takes all the light that hits its large surface and focuses it down to a small spot the size of your pupil. This primary mirror is mounted at the bottom of a tube, the tube just holds everything together.

So now the primary mirror is reflecting all the light back to the front of the tube. But if you look down the tube, you block all the light. This is where the secondary mirror comes in. This secondary mirror is a small flat fellow that sits inside the tube, and reflects the concentrated spot of light out the side of the tube.

Now at the side of the tube is the eyepiece and focus mechanism. All the magnification comes from the eyepiece. The magnification can be calculated as the ratio of the eyepiece focal length to the primary mirror focal length.

Mechanical Stability

When you are looking at something far far away with a very narrow viewing angle, it is very important that your telescope is not bouncing around. The tiniest little shake gets magnified many many times to make objects look like they've just been hit with an atomic baseball bat.

My telescopes specs and part list

I bought all the optics for my telescope from a surplus site called "The Surplus Shed" there's a link at the bottom of this page. Here's what I bought:

-4.5" F/8 36" focal length primary mirror with adjustable mount, secondary mirror w/mount and spotting scope: $29.75 from the surplus shed.
-Reflector focuser assembly (really junky): $19.95 from the surplus shed.
-25 and 12.5 mm focal length PLOSSL eyepieces: $28.50 each from surplus shed.
-6" Nominal diameter PVC pipe, 5 ft long: $25.93 from McMaster-Carr
-6" Nominal diameter PVC pipe cap (lens cap): $9.75 from McMaster-Carr
-Monster BOGEN tripod: FREE from the nice dumper at Stanford
-Misc. hardware..nuts and bolts..

So this comes to a total cost of about $150 bucks. Not too bad I'd say. I'll bet you couldn't touch one in the store for that price and it was really fun to get working.
Here are a couple of photos; down the tube and a view of the spider (mount that holds the secondary mirror). And a couple shots of the moon...

DISCLAIMER

The author assumes no liability for any incidental, consequential or other liability from the use of this information. All risks and damages, incidental or otherwise arising from the use or misuse of the information contained herein are entirely the responsibility of the user, have a nice day!

Last updated: 06/20/03
Copyright 2003, Greg Miller
http://www.angelfire.com/80s/sixmhz/telescope.html