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.
