Sky and Telescope - September 2018 - 72

ASTRONOMER'S WORKBENCH by Jerry Oltion

A New Generation
Picks Up the Torch
Zane Landers carries on the grand tradition of telescope making.

I CONSTANTLY HEAR PEOPLE FRET

about the aging of amateur astronomy
and bemoaning the decline in popularity of amateur telescope making. While
there is definitely some truth in both
concerns, Connecticut amateur Zane
Landers is quietly proving those fears to
be unfounded.
Zane has been into astronomy since
he was 12, which was only three years
ago. He started with a 4-inch Go To
Maksutov that he got for Christmas,
but soon became frustrated with
the telescope's computer system and
its small aperture. He switched to a
6-inch Edmund Newtonian, which he
reports "had good optics and worked
very well except for the fact that it
weighed 70 pounds, looked really ugly,
and had stray light problems due to its
very short tube." So he tried a 4-inch
refractor, which was lighter and more

attractive than the Edmund scope but
was uncomfortable to use. So he sold
the refractor and bought an 8-inch
Schmidt-Cassegrain, but the optics
were terrible.
Unhappy with commercial scopes,
Zane decided to make his own instead.
In May of 2017 he started grinding
a 6-inch blank using an old Edmund
Scientific mirror kit, and he got it to a
nice f/7 curve in relatively short order.
Then he made his first major mistake:
He decided to use the original rouge
and pitch supplied with the 50-year-old
kit. He added oil to the pitch to soften
it, but the resulting tool was way too
inconsistent in hardness and soon got
stuck to the mirror.
Zane says, "I tried everything to
get the pitch off, but all that resulted
was a chipped mirror still stuck to the
pitch lap. I did get them separated and

p Zane's second completed scope is a 16-inch f/5 (seen at left), which required that he refigure
the primary mirror (right).

72

S E P TE M B E R 2 018 * SK Y & TELESCOPE

finished polishing/figuring with Gugolz
and cerium oxide, but the chips (and
a fracture near the edge) meant that it
wasn't worth it to get it aluminized and
build a scope out of it."
But Zane didn't give up. At Stellafane
last summer he was given a 6-inch f/5
pre-generated blank from renowned
ATM Dave Groski, who said he could
have it for free but he couldn't chip the
edges this time.
The grinding phase went very well,
and the mirror didn't stick to the pitch,
but after polishing for what Zane terms
"a ridiculous amount of time (probably dozens of hours) to give the mirror
as perfect a polish as I could give it," a
Ronchi test revealed a severely turneddown edge.
"I polished like a maniac for about
14 hours over the course of a few days
with short strokes to remove it," Zane
said, and he was successful. Parabolizing was fairly straightforward, although
it took about five times as long as the
books and websites he consulted said it
would. When he was finished, the mirror came in at f/4.5. Total time on this
mirror: two and a half weeks.
Zane sold his 8-inch SCT to finance
construction of the scope for his new
mirror. He used an 8-inch Sonotube
lined with cork painted flat black, and he
made sure to extend the tube far enough
to shield the focuser from stray light.
As for the mount, Zane says, "I'm
proud of this part. I'd never done any
woodworking before and only used a
drill maybe once previously." Yet he

Z A NE L A NDERS (4)

u This sharp smartphone photo of the Moon
captured through Zane's 6-inch Dobsonian
attests to the excellent quality of his optics.



Table of Contents for the Digital Edition of Sky and Telescope - September 2018

Contents
Sky and Telescope - September 2018 - Cover1
Sky and Telescope - September 2018 - Cover2
Sky and Telescope - September 2018 - 1
Sky and Telescope - September 2018 - Contents
Sky and Telescope - September 2018 - 3
Sky and Telescope - September 2018 - 4
Sky and Telescope - September 2018 - 5
Sky and Telescope - September 2018 - 6
Sky and Telescope - September 2018 - 7
Sky and Telescope - September 2018 - 8
Sky and Telescope - September 2018 - 9
Sky and Telescope - September 2018 - 10
Sky and Telescope - September 2018 - 11
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Sky and Telescope - September 2018 - 14
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Sky and Telescope - September 2018 - 17
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Sky and Telescope - September 2018 - 21
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