My first Magazine Sky & Telescope - 03.2019 | Página 38

TELESCOPE CARE
by Jerry Oltion
ALL MIRRORS ARE EQUAL
Whether you use a tabletop
refl ector or a giant Dobsonian, all
Newtonian refl ector mirrors re-
quire a good cleaning eventually.
Nurture
YOUR NEWT: Bathing Mirrors
ewtonian telescopes are amazingly robust devices.
With two mirrors that need to be accurate to within
¼-wavelength of light and aligned within millimeters,
you might expect them to be fussy, temperamental beasts
that require constant attention and adjustment. Some people
do seem to fi ddle with their scopes more or less continually,
but others let them go for years without so much as a dust-
ing or a twist of a collimation knob. The famous Edmund
Astroscan, one of the best-selling Newtonian designs in his-
tory, wasn’t even built to be adjustable.
Yet while it’s true that the Newtonian is tolerant of
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neglect and even some abuse, it’s also true that a little care
and fi ne-tuning can keep your scope operating at peak
capacity. Two of the simplest and most effective main-
tenance tasks are surprisingly easy: keeping it clean and
keeping it collimated. We’ll talk about cleanliness here and
collimation next month.
Dust Prevention
Regarding cleanliness, the main thing you need to concern
yourself with is dust on the mirrors. It’s surprising how much
they can collect and still provide a decent view (by “surpris-
ing,” I really mean “Holy, cow, you’ve got to be kidding!”),
but there’s a limit. Every speck of dust adds a little diffraction
to the image, and eventually all that diffraction adds up to
become a distraction.
Cleaning your refl ector’s optics ensures
top performance.