William Optics ZenithStar 66 SD APO Manuel d'utilisateur télécharger pdf (Page 3)

really catches your eye. What gets your atten-

tion is a smaller knob centered on the right

focus knob. This yields 10 to 1 reduction for

fine focusing. The action of this slow speed

control is even smoother than the course-

focus, and is a real boon for higher power use

and, especially, imaging.

One other thing I liked about the WO

focuser was that it’s rotatable. Loosen a set-

screw, and you can rotate the focuser to

change eyepiece or camera angle. Like slow

speed focus, this is a feature that was for-

merly unknown in telescopes in this price

range.

Focusers are cool, but what good is a

focuser if the objective brings back that

moldy-oldie “Purple Haze”? Let's pull the

gold-colored lens cap off and take a look at

what’s up front – an f/5.9 doublet objective

with an FPL-53 “fluorite” glass element.

What you’ll actually see is this: not much.

The lens is coated with WO's STM formu-

lation, and these multi-coatings tend to

make the glass disappear. The cell this objec-

tive sits in is not adjustable, but I've yet to

hear of one of these scopes arriving miscolli-

mated or needing collimation later. Stuff

happens, of course, and one of the reasons

to buy the WO 66 rather than a similar

scope is support. If you have trouble, WO

will fix it in hassle-free fashion.

Let’s do the flashlight test.

Yeah, I know I tell

y’all

not to point a bright,

oblique light at a lens or

mirror—it just serves to make ‘em look hor-

rible, usually. But do as I say, not as I do.

Anyway, even in the glare of a flashlight, the

WO objective looked very fine. The bright

light also served to illuminate the tube inte-

rior, revealing a series of baffles designed to

keep stray reflections at bay. These are real

baffles, incidentally, not the not-so-hot foam

baffles WO used way-back-when in their

original Megrez 80-mm achromat.

Specifics aside, what was my general

impression? Just this: that the scope was both

pretty and solid. The tube, a nice-

ly finished black (that unfortunate-

ly showed fingerprints very easily),

was built like a little tank, coming in

at a surprising 3.5 pounds, which is

about the same as the larger-aper-

ture Short

Tube 80.

“Pretty” is

good, sure,

but how

would she

do under the stars?

“New scope curse”? It’s real, boys and

girls. It was weeks before I got a chance to

tote this elegant-lookin’ little scope out to

my club’s dark site near the metropolis of

Tanner-Williams, Alabama. It was a muggy

evenin’, just as you’d expect in late August

down on the Gulf Coast. Nevertheless, the

Milky Way was dramatic away from

Mobile’s light-dome, and the burnished stars

of summer beckoned in the heavy air. I wast-

ed no time getting the wee scope setup.

Which brings up an important ques-

tion: what do you set the 66 on? There are

plenty of options. I’ve used a heavy duty

Manfrotto camera tripod, and I’m sure the

scope would be great on William Optics’

EZ-Touch alt-az mount. But I chose to place

the Zenithstar on my Celestron CG5

mount. Not only did this provide an

absolutely rock-solid platform for the refrac-

tor, but it also gave me go-to and would, I

hoped, allow me to do some deep sky imag-

ing.

Was there anything I was worried about

regarding the 66? Well, yes: A-P-E-R-T-U-

R-E. I’ve long preached “aperture always

wins,” and 66 mm, 2.6 inches, just ain’t

much. It turns out this is not a huge concern,

however. If you you’re okay with what a

Short Tube 80 can show, you’ll be happy

with what you see in the 66. Anything I

could see in an ST80, I could see in the 66

SD, and, thanks to the higher quality optics,

I was usually seeing it better.

One of the things I disliked about the

ST80 was the difficulty it had with globular

clusters. No matter how high I pushed the

magnification, it was unable to resolve stars

Astronomy TECHNOLOGY TODAY

WILLIAM OPTICS ZENITHSTAR 66 SD APO PATRIOT EDITION

Aperture 66 mm

Focal Ratio f/5.9

Focal Length 388 mm

Objective Type SD Doublet, Air Spaced, Fully Multi-Coated

Resolving Power 1.78"

Limiting Magnitude 10.8

Lens Shade Retractable

Focuser 1.6" (40.6 mm) Dual Speed Crayford, 1:10 Fine Focus

63 mm (2.5") Focuser Travel Length

Rotatable Focuser Design

Accepts 2" SCT diagonal for 2" accessories

2" adapter available for astrophotography

1.25" Adapter Brass Compression Rings

Field Stops 10 Baffles

Tube Diameter 2.95" (75 mm)

Tube Length 11.8" (300 mm) Fully Retracted

14.2" (360 mm) Fully Extended

Tube Weight 3.5 lbs. (1.61 kg)

Case Aluminium Case (Standard)

Case Dimensions (WxHxD) 15" x 9.6" x 6.5" (38.5 cm x 24.5 cm x 16.5 cm)

Case Weight 3.5 lbs. (1.6 kg)

PRETTY LITTLE PATRIOT

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William Optics ZenithStar 66 SD APO Manuel d'utilisateur Page 3

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