Sky-Watcher
Equinox 80ED Review
Sky-Watcher’s Evostar 80 ED DS-Pro
is a popular telescope these days. Its combination of modest price, easy
mounting and usefully wide field make an ideal starter’s imaging scope. But
Sky-Watcher once made another 80ED – the Equinox 80ED – that was a completely
different scope, both mechanically and optically.
Here I take a look at the differences
between the Evostar 80ED DS-Pro and the Equinox 80ED and compare the Equinox to
a premium scope of similar aperture and focal length, the Tele Vue TV-76.
At
A Glance
|
Telescope |
Sky-Watcher
Equinox 80ED |
|
Aperture |
80mm |
|
Focal
Length |
500mm |
|
Focal
Ratio |
F6.2 |
|
Length |
~370mm |
|
Weight |
2.9 Kg |
Data from Me/SW.
What’s
in the Box?
Like others in Sky-Watcher’s premium
Equinox range, all you get is an OTA and case, but the case is a higher quality
one than the Evostar model, with proper cut camera-case foam instead of
ethafoam.
Design
and Build
The 80ED was once available in two ranges, the Evostar 80ED DS-Pro
and this Equinox.
The Evostar 80ED DS-Pro was the cheaper of the two, with a
fixed dew-shield and a rolled tube in their familiar ‘black diamond’ (i.e. white and metallic black) colours with a white cast
focuser. It’s the only 80ED doublet Sky-Watcher sell now (they make a much more
expensive and heavier triplet too).
The ‘other’ Sky-Watcher doublet 80ED, the Equinox on review
here, is different. For one thing, it comes in a shiny black all-CNC tube with
a sliding dewshield and CNC focuser. But unlike the larger (100ED and 120ED)
Equinox models, the optical spec’ is different too, as we’ll see ...
Update 2021: The Equinox range was once available in 66mm,
80mm, 100m and 120mm (see below) apertures; they’ve all been discontinued. Only
the Evostar DS-Pro model is currently available.
Sky-Watcher’s Equinox range once went all the way up to this superb
120ED.
The alternative Evostar 80ED DS-Pro model has the standard SW
‘Black Diamond’ livery with a cast focuser.
Optics
The most
important thing to understand is that Equinox 80ED is F6.3 (500mm focal
length), whilst the cheaper ED Pro is F7.5 (600mm focal length). Why? No idea. Does
this matter? Well, on one hand, the ED DS Pro’s longer focal length
significantly increases exposure times for deep sky imaging. Whilst on the
other, the slower lens has the potential to show less aberrations, both
chromatic (false colour and spherochromatism) and monochromatic (like astigmatism,
coma and field curvature that distort star images in the outer parts of the
field).
Otherwise,
the lenses are both ED doublets that are Chinese made, but use glasses from premium Japanese/European
brands. Sky-Watcher have strongly marketed their use of Ohara’s FPL-53 for the
positive crown element and a high-grade flint from Schott for the negative. FPL-53
is one of the best high-fluoride ED glasses around and is used in many of the
best apochromatic lenses.
The lens
appears well coated (perhaps better than the typical ‘China green’ used on the
ED Pro) and sits in a slim, non-adjustable cell.
Tube
The Equinox sports lots of piano-black, too many
chrome parts and is a bit too shiny generally. However, the Equinox is beautifully built, whatever you think of the
shiny finish. What
looks like chrome is chrome, i.e.
metal and not plastic (though I’ve heard it can flakes off). The tube looks
plastic, but it isn’t - it’s beautifully anodised metal too, which is why the
Equinox is heavy. In fact, the external build quality of the Equinox is almost too good, too slick and polished; it
looks a bit cheap and flashy, a bit flat-screen TV, especially compared with
something like a Tele Vue 76.
The other disadvantage of that CNC tube is that it’s fairly
heavy for a scope of this size – about 2.6 Kg. For comparison, the Equinox is a
lot heavier than either the Borg 90FL or Takahashi FC-76DC.
Look past the 80ED lens and you find concentric ridge baffles
finished in matte black and a generally high level of internal quality as well.
Focuser
The Equinox focuser is a standard premium Chinese Crayford
with a dual speed knob on the right. Mostly it’s made of anodised CNC-machined
metal like the tube and is very precise and smooth in operation. I can detect no play in the drawtube, even at
full stretch, which is great news for imagers. Not only is it smooth, but the
focuser has lots of travel, with a scale for imaging. The focuser remains
smooth even with heavy eyepieces.
The Equinox throws in a final feature anyone using refractors
on equatorial mounts will appreciate: a rotator for the focuser. The knurled chrome
ring in front of the focuser twists to free the whole focuser for rotation. It’s
intended as a camera rotator – allowing perfect framing for imaging - but I
love rotators for visual use too: you can adjust eyepiece position without
risking dumping an expensive diagonal and eyepiece on the floor. The Equinox
rotator is a bit stiff, but is still a useful feature.
Mounting
The larger
Equinox models come with tube rings, but the 80ED (and the 66ED too) have a
small Vixen (EQ5) compatible dovetail plate attached directly to the tube. This
is a less flexible solution than rings, but at least there is a standard ¼-20
thread on the bottom for a camera tripod.
The Equinox
80ED is a bit heavier than the Evostar 80ED DS-Pro, but it still mounts on just
about anything, photo tripod and head included (as shown here). You could
certainly start off with an EQ5 for imaging, especially since the short focal
length will be less fussy about tracking errors.
Sky-Watcher’s
Equinox 80ED (right) on a photo tripod, next to Tele Vue’s TV-76.
Accessories
The Equinox lacks the diagonal,
eyepiece and finder you get with the ED Pro, but the case is finer quality and
lined with proper foam not packaging style ethafoam, like the Evostar 80ED DS-Pro’s.
In
Use – Daytime
Daytime views are sharp, but
high-contrast subjects do show some false colour, as you can see from the photo
of one of my local Jackdaws below. False colour is a little worse than a Tele
Vue TV-76.
This is slightly curious, because the 120ED
– supposedly made with the same glasses – has much lower levels of false colour,
despite being a much larger aperture and only 1.5 Fs slower at F7.5 vs F6 for
this 80ED.
As this image shows, daytime views and
photos through the Equinox 80ED are sharp but reveal some false colour.
Deep sky images show some field
curvature at the edges, but good coverage. Brighter O-A stars reveal some
bloat.
Cropped image of the Moon in twilight
through Equinox 80ED shows good detail.
In
Use – Astrophotography
The 80ED produces wide, sharp deep sky
images. Bloating on bright O-A (blue-white) stars is typically a bit worse than
the image above suggests, in which none of the stars are really bright. Field
curvature on APS-C isn’t too bad, but a keen imager will want to get a good
flattener or reducer.
Images of the Moon are small due to the
short focal length (and thus image scale), but sharp and detailed nonetheless
(see above).
In
Use – Observing the Night Sky
General
Observing Notes
The Equinox
is a refined scope to use. The focuser is smooth, largely free of image shift
and accurate with its fine-focus knob. The long retractable dewshield protects
the objective well. The view is generally good, though perhaps not quite as
good as the (much more expensive) Tele Vue TV-76 I was testing alongside.
Cool
Down
Cool down for a small doublet like this
is fast, ideal for quick looks between showers.
Star
Test
The star test
looked pretty good, with nice diffraction rings either side of focus.
The
Moon
The Moon
showed good detail and took higher powers quite well, but I noticed more stray
light bleeding into the black space around the Lunar limb than I did with the
TV-76 and I thought contrast was slightly
poorer too.
Mars
Turning to Mars just after opposition, with a disk size of
about 14 arcsecs, views were much the same through the 80ED and TV-76, though
the altaz mounts we were using were awkward at the high powers needed to
resolve detail. Nonetheless, Syrtis Major was clearly
seen in both scopes at 120x, a magnification which still yielded a sharp image
with the Equinox 80. I couldn’t see much difference between the two scopes on
Mars, but thought high-power focus was a little snappier in the Tele Vue.
Deep
Sky
If the Moon through the Equinox seemed a bit soft compared to
the near-perfect view through the TV-76, the same couldn’t have been said of
the deep sky objects we viewed earlier, before Moonrise. Both scopes gave a
commendably flat sharp field, with excellent definition on the Orion Nebula and
pinpoint stars in the Trapezium. Contrast on the nebulosity was much the same
in both scopes, but I thought stars were a bit tighter and more diamond-like in
the TV-76, though the difference was tiny.
My observing buddy noted that the view through the ED80 seemed
wider and I agreed. When we checked, the FOV was much the same, as expected,
but the fainter stars in the ED80 were brighter due to its larger aperture
(80mm vs 76mm = 10% more light gathering).
The Andromeda Galaxy, M31, was similar in both scopes and
looks great at this focal length which gets much of the galaxy in the field in
a way bigger scopes just can’t. Short focal length
refractors like this excel on star fields and open clusters, like those running
up through Auriga (see image of M36 above).
Summary
If you want a lowish cost wide-field astrograph, then the
Equinox 80 is an excellent choice if you can find one, thanks to its fast lens
and accurate dual-speed focuser. It might make a better imaging scope than the Evostar
80ED DS-Pro version.
You would need a flattener or reducer for serious or
full-frame imaging, but this focal length leaves you spoiled for choice when it
comes to reducers, with options from Tele Vue through William Optics and Borg
too.
The Sky-Watcher Equinox ED is not bad as a grab-n-go or
travel scope either, though a bit larger and heavier than the TV-76 that I was
testing alongside. It will mount on most small mounts for visual use, including
photo tripods.
Performance for both visual and imaging aren’t quite up to
the premium standards of Tele Vue, Takahashi and Borg - with slightly less
glitteringly pinpoint stars and more scattered light on bright objects like the
Moon - but then neither is the price.
The Sky-Watcher Equinox 80ED is
recommended as a grab-n-go visual scope or budget astrograph.
Updated by Roger Vine 2021
Sky-Watcher’s Equinox 80ED alongside
Tele Vue’s TV-76.
Buy Sky-Watcher Evostar 80ED DS-Pro from Wex here:
