16" / 406.4mm Aperture 1826mm Focal Length, f/4.5 Focal Ratio 10:1 2" Two-Speed Helical Focuser Red-Dot LED Finderscope Floor-Based Manual Alt-Az Mount Altitude Tension Clutch Dual Radial Main-Mirror Fans Tool-Free Breakdown and Assembly This is a Generation II telescope . All updates have been performed on this telescope.
No telescope type has influenced amateur astronomy as radically as the dobsonian telescope. Before the introduction of this telescope type by John Dobson the vast majority of amateur telescopes were small inadequate refractors on shaky mounts - just good enough to show the polar regions on mars or the rings of Saturn. Bigger telescopes, like the Schmidt-Cassegrain telescopes, were restricted to the relatively small group of amateurs that could afford them.The brilliant combination of simple - but effective - mechanics and the largest aperture available led to a worldwide triumph of this concept. No other telescope type offers you so much light for your money as a good dobson. We have taken the motto "held together by gravity and driven by yoghurt power" and offer a modern version of the classic - designed by amateur astronomers for amateur astronomers. Despite its large aperture the telescope can be transported easily even in small cars and is assembled within minutes without tools. The construction was optimized for maximum rigidity with a minimum of mass. The combination of big altitude wheels and a optimized aluminium-sandwich construction allows for small movements even at high magnifications. The focus position is already positioned to accept our coma-corrector. The ideal workhorse for the deep-sky enthusiast. A telescope with 406mm aperture gathers more than 3300-times more light than the naked eye. Details on planetary surfaces stand out even to unexperienced observers, and countless deep-sky objects show details. Bright globular clusters are resolved down to the core and the view of the lunar terminator will provide a unforgettable experience.
Dimensions for mobile use: Rockerbox 550mmx550mmx330mm; Mirrorbox 480mmx480mmx300mm; Trusses approx. 1250mm
Modern 406mm truss-dobsonian telescope in full aluminium construction
Specifications:
Optical design Newtonian Reflector
Mount Type Dobson
Objective diameter (mm) 406
Focal length (mm) 1826
Magnification (with included accessories) up to 800
Warranty (Years) 3
Focus Group Advanced Amateurs
Visual enthusiasts
Power supply 1) 12V Batteries or mains adapter
Rain/Dust protection caps Dust protection caps for open aperture and eyepiece holder
Aperture ratio 4.5
Angular resolution (arc seconds) 0.32
Mount type Dobson
Transportability very good
Field of application Deep Sky Observation
Lunar observation
Planetary observation
Obstruction (%) 25
Primary mirror diameter (mm) 406
Material OTA Metal
Colour black
Focusing system 2" Crayford-Focuser with 10:1 Reducer
Finderscope LED-Red Dot Finder
Material Primary mirror BK-7
Explore Scientific 16" f/4.5 Truss Tube Dobsonian Telescope
Collimation Assist Tool
Red Dot LED Finderscope
Limited 1-Year Warranty, Extendable to Transferrable Lifetime Warranty with Registration
Suggested Accessories: 2-inch HR Coma Corrector ; Explore Scientific Waterproof Eyepieces ; Focal Extenders
VIDEO
VIDEO Reviewed by Steve Collingwood / Images: www.thesecretstudio.net
Dobsonians remain a firm favourite with amateur astronomers seeking
manageable and affordable large aperture telescopes. Though the simple
altaz design of the Dobsonian mount has seen many refinements over the
years, at its heart it is still an incredible piece of engineering.
This 16-inch truss tube offering from Explore Scientific is shipped
in one box, with the rocker and mirror box pre-assembled and the other
components ready to fit together by way of thumbscrews. While many
commercial Dobsonians use rolled steel tubes and wooden rocker boxes,
for this instrument they have been constructed from aluminium. The
low-profile square design of the rocker and mirror boxes allows for a
very strong and remarkably efficient system indeed. This is great if you
want to travel to a darker location for a night’s observing or have
limited storage space.
The 16-inch primary mirror is made from BK-7 glass and has a focal
length of 1,826mm, giving a focal ratio of f/4.5 –a short focal length
for its size. The dual-speed 1:10 rack and pinion focuser is well made
and can easily support heavier eyepieces. The unit felt very responsive
with no image shift in use with a range of eyepieces. An extension for
the drawtube is supplied.
Our initial assembly progressed slowly at first, as some of the
internal threads were poorly cut on our review scope, but once rectified
we were able to put the telescope together with relative ease. The
instrument has clearly been designed so it can be assembled by one
person. Although we found this a little tricky at first, after a couple
of times it was no trouble at all.
We took the telescope out under the night sky with our own eyepieces,
as none are supplied out of the box. Allowing the optics to reach
ambient temperature for optimum performance can often take quite a while
with larger optics, but the in-built cooling fans allowed the telescope
to cool down sufficiently in less than 30 minutes. These fans are
powered by eight D batteries (not supplied); their battery box can be
strapped to the body of the telescope.
Unusual collimation
Collimation out of the box was close, but did need minor adjustment.
Aligning the optics only took a matter of minutes. Primary mirror
adjustments are made from the front of the mirror using the supplied
long-reach collimation tool.
Care needed to be taken to avoid touching the mirror’s surface, but
aside from that this method proved remarkably quick and effective.
Secondary adjustments are made with large thumbscrews located behind the
secondary mirror mount and, while unusual, they worked extremely well,
enabling the whole operation to be carried out while still at the
eyepiece.
Once cooled and collimated, we aimed the telescope at the Orion
Nebula, M42. With a 30mm eyepiece we were greeted with a wonderfully
rich view of the nebula and the stars in the centre. We then increased
the magnification and moved on to Jupiter, revealing plenty of contrast
and detail on the bright planet. Framed by the four Galilean moons,
Jupiter was an impressive sight even though seeing conditions were
relatively poor. However, we did find accurately sighting the telescope
quite tricky, as the supplied red-dot finder was not very sturdy. Once a
target was centred, the large wheels and base-bearing surface ensured a
positive movement, enabling smooth and accurate tracking and good
balance.
Overall this instrument was a pleasure to use, though the finishing
touches on the telescope weren’t as good as they could have been –
giving it a more of a ‘prototype’ feel. Yet these can be considered
minor issues as it is extremely practical.
The excellent optical performance and compact, lightweight nature of
this Explore Scientific Dobsonian remain true to John Dobson’s original
design ethos while also giving a design update and superb performance.
Easy to put up, easy to take down
Larger aperture Dobsonian telescopes can be difficult to manage in
terms of assembly, storage and transport, but this instrument is
amazingly compact and portable for its class. Its mirror box footprint
of 55x55cm is tiny in comparison to many other 16-inch Dobsonians. We
found that it could be easily carried through doors, and would even sit
on the back seat of many cars. The box also has a hinged lid, ensuring
that the mirror inside is protected when stored.
The low-profile head assembly is constructed from the same aluminium
profile as the mirror box and rocker box, so is exceptionally light and
easy to handle. We found that even after transporting and assembling the
telescope several times, the optics required only minor adjustment.
Throughout its design and construction, practicality seems to be the
key. Lightweight materials coupled with basic construction techniques
have really made the telescope very usable indeed.
Focuser - The supplied 2-inch rack and pinion
focuser has a 1:10 reduction for fine focus. The drawtube can also
unscrew to accommodate the supplied extension barrel.
Primary collimation - Adjustments to the alignment
of the primary mirror are made from the front of the mirror cell rather
than behind it. This enables accurate collimation to be achieved more
quickly, and without having to step away from the eyepiece. Doing this
requires a special tool, which is supplied.
Secondary collimation - No tools are needed to
collimate the secondary mirror. Adjustments are made via thumbscrews
located behind the assembly, rather than the traditional point of
directly above. This innovative approach allows easy access while
reducing the risk of anything falling onto the primary mirror.
Altitude wheels - The large altitude wheels proved
to be really useful. Making small movements at high magnification can be
difficult with telescopes of this size, but the larger diameter
trunnions not only provide a smooth and positive feel but also aid
balance when using a range of eyepieces.
Cooling fans - The mirror box houses two battery
operated fans: one ‘pushes’ cold air into the mirror box and across the
surface of the mirror, while the other ‘pulls’ warm air out. The fans
were quiet and effective in operation.
This review originally appeared in the June 2015 issue of BBC Sky at Night Magazine.
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