Telescope Making Diary: Week #2

Day 8: Going Round in Circles

Routing a circle

Routing the hole for the top of the mirror box.

Cutting neat, tidy circles in plywood. This is where a plunge router really shines. And make no mistake — building a Dobsonian means cutting circles. In the case of my scope’s design, the first ones are for the tube ring and for the flange at the back of the tube, where it mates with the mirror box.
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Telescope Making Diary: Week #4

Day 22: Completing the Upper Tube

Complete upper tube

The scope’s upper tube all done. The gloss-black finish is achieved with Monokote.

With the mirror box done, it was time to move on to the comparatively straight forward job of finishing up the top half of the scope. This consisted of two tasks: giving the cardboard tube a protective covering and attaching all the hardware.
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Beat the Heat: Conquering Newtonian Reflector Thermals — Part 1

Newtonian thermal gradient

What you need to know when it comes to optimizing your scope’s thermal behavior.

Generations of backyard astronomers have debated why, inch-for-inch, the performance of a high quality refractor usually edges out an equal-quality Newtonian reflector. This disparity is most apparent when viewing low-contrast planetary detail — the images in a good refractors often have a touch more snap to them. Is there some intrinsic shortcoming in the design of the Newtonian reflector that makes this inevitable?
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Houston Astronomical Society Interview

GuideStar header

I was recently interviewed for the Houston Astronomical Society’s newsletter GuideStar. I’ve been interviewed a few times before and have found that the quality of the resulting article depends hugely on the interviewer. Prep is everything. And in this case, Clayton Jeter was a real pro. His questions were thoughtful and interesting, and clearly the result of having done his homework.

The complete interview appears after the jump.
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Complete S&T Index from 1997 to 2009


Here is a listing of every article I’ve written for Sky&Telescope magazine up to the end of 2009. The index is in chronological order and gives the year, month, page number, department heading, and title. You can do a keyword search using your browser’s search function (activated by pressing Ctrl and F simultaneously) if you’re looking for a specific item.
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How To Build A Curved-Vane Secondary-Mirror Holder

Curved spider

The secondary mirror holder and spider on my 12¾-inch truss-tube Dobsonian is made with scrap wood, a few nuts and bolts, and a stainless-steel ruler.

The curved-vane secondary mirror holders I use on almost all my telescopes never fails to excite curiosity. Most people know that the principal benefit of the curved spider is spike-free stars, but they often wonder if it really works. The “points” adorning bright stars in telescopes with straight-vaned spiders are diffraction artifacts that don’t seriously affect the image but do impose an aesthetic quality that may not appeal to you. Luckily, the remedy is easy to make, works like a charm, and can be retrofitted to virtually any reflector — commercial or homemade.
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