Kowa TS-501 Review
This is the first (and may remain the only) review of a
spotting scope on ScopeViews! The reason is that prismatic scopes, great for
erect-image nature viewing, are a bit limited for astronomy because the prisms
typically distort star images and prevent high magnifications. To use a
spotting scope for astronomy at all requires the highest optical and mechanical
quality. Kowa interested me because they have a reputation for delivering that
(Japanese made) quality at a much lower price than the main premium brands.
Their entry level model, the TS-501, has potential as a travel scope because it
is tiny, feather-weight and rugged.
Design and Build
The TS-501, effectively including diagonal and eyepiece,
makes traditional travel scopes look big and bulky. It must weigh under a kilo
and fits on your palm.
Simple eyepiece giving a narrow field and modest eye relief.
50mm lens has single coatings (or perhaps very basic
multi-coatings).
Optics
The TS-501 has a built-in eyepiece giving a magnification of
20x. The eyepiece is not interchangeable on this model. The eyepiece is angled
at 60 degrees, but they also made an otherwise-identical straight-through
version.
The lens is a 50mm achromat with what appear to be single
coatings.
Tube
The body is made of some kind of tough plastic –
it’s not pretty, but you can tell it would stand up well to outdoor
rigours. It is not sealed and purged, but looks as if it would withstand a
heavy shower without problems.
Focusing is by an internal mechanism like all spotting
scopes: you just twist the yellow knob.
In Use - Daytime
The TS-501 is quite basic, but in terms of quality it’s
good: the focuser is smooth and accurate, the lens well-figured and everything
perfectly collimated.
The view is good too, but the field of view is narrow and the
eye relief too small for use with specs. My guess is that – in line with
the rest of the scope – the eyepiece is a fairly simple design.
In Use – The Night Sky
At night, the small aperture and single coatings, plus the
light-robbing prisms mean the view is rather dim and that, combined with a
narrow field of view, make finding things hard. So if you do use this for
astronomy it will be for the Moon and bright planets, not deep sky objects and
star-fields. There is a big difference with a dedicated astro-scope here.
The MiniBorg 50 has the same
aperture and is actually amazingly good on the brighter DSOs.
The Moon
So if you point the TS-501 at the Moon, what can you see?
Quite a lot actually. The image is sharp and crisp; chromatic aberration,
whilst present on the limb, is well-controlled. I’ve seen cheap spotting
scopes that make a real mess of the Moon, but not this one.
Most of the main features, the Maria and larger craters, are
visible. You can see Tycho and its rays, the Sinus Iridium, Copernicus and its
central peaks, dark-floored Plato, Mare Criseum and bright Proclus. You could
certainly buy an atlas (or a Smartphone app these days) and start to learn your
way around Luna’s enthralling alien and rugged topography with the
TS-501.
Planets
Unfortunately dazzling Venus always causes flare in prismatic
systems, obscuring its phase. The Outermost planets are too faint to find
easily in any 50mm scope, never mind one with a dim narrow field and no finder.
That leaves Mars, Jupiter and Saturn on the TS-501 observing schedule.
Mars is just a red dot at 20x. Saturn reveals a hint of its
rings in the form of the ‘jug handles’ familiar from
Galileo’s drawings (he was using about 20x too). Jupiter impresses with
all four Galilean moons and both main cloud belts – the north and south
Equatorial Belts (NEB and SEB). Again, many prismatic systems – both
scopes and binos – make a real mess of Jupiter with just a flared blob in
place of a planet, but not so the TS-501.
Deep Sky
The only one I was easily able to locate and view was M42,
The Great Nebula in Orion. Due to its magnification, the TS-501 showed more of
M42’s arching shape than binoculars, but only the bright central region
of nebulosity was visible.
The dim optics meant the Pleiades lacked their customary
refractor glitter.
Summary
The TS-501 delivers on the Kowa promise of quality. There is
nothing glamorous about it, but optical quality is high and the focuser smooth
and accurate. For astronomy it is limited, though and not just by its small
aperture. The single coatings and prism system seem to waste a lot of light, so
the TS-501 is really too dim for all but the brightest DSOs (i.e. M42). However
the 20x magnification and sharp optics will show a fair bit of detail on the
moon and the main belts on Jupiter. If you want a tiny travel scope, though, a
Mini Borg 50 will show you a lot more and is the better bet, unless you really
need the semi-sealed and rugged Kowa.
Not recommended to buy specifically for astronomy, but quite
usable for quick looks at the moon and Jupiter (unlike most cheap spotting
scopes!). Or shove it in your bag for a peek at that upside down Moon in
Aussie.
