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Best for
A first telescope for someone who wants to sweep the sky rather than study one object
A grab-and-go companion to a larger, slower telescope
Low-power views of comets and large clusters
Not ideal for
Planetary detail or lunar photography
Any form of deep-sky astrophotography
Splitting close double stars
Purpose scores
The same four purposes are scored for every telescope on this site, using the same weights. A telescope that is excellent for one is often poor for another — that is the point.
Scores are relative to every telescope on this site, not absolute quality marks. A 6.5 for galaxy imaging and a 6.5 for visual observing do not mean the same thing. How scoring works.
Optical design
The StarTravel 102 is a two-element air-spaced achromat working at f/4.9. Two elements cannot bring
all wavelengths to the same focus, and the faster the system the more visible that failure becomes.
At this focal ratio the residual violet halo around bright objects is not subtle — you will see it
on the Moon’s limb the first time you look.
That is the trade the design makes deliberately. In exchange you get 102 mm of aperture in a
460 mm tube weighing under 2.5 kg, with a true field approaching four degrees using a 2-inch
eyepiece. Nothing else at this price frames the Double Cluster the way this does.
Visual observing
On extended low-surface-brightness targets — large open clusters, the Milky Way through Cygnus, a
bright comet’s tail — this is a delight, and the false colour is essentially invisible because
nothing in the field is bright enough to provoke it.
Push past about 100× on the Moon or Jupiter and the picture changes. The violet halo intensifies,
contrast falls away, and a 90 mm Maksutov costing similar money will show more planetary detail.
Treat the StarTravel as a rich-field instrument and it is excellent; treat it as a general-purpose
telescope and it will disappoint you on half the sky.
Nebula imaging
The focal length is in exactly the right window for large emission nebulae, which is why this
telescope keeps being suggested as a cheap astrograph. It is not one. Without a field flattener the
corners of even an APS-C frame show obvious elongation, and the uncorrected blue channel produces
bloated, halo-ringed stars across the whole frame. Narrowband imaging through a single filter
sidesteps the colour problem but not the field curvature.
If wide-field imaging is the goal, a small ED or Petzval refractor at a similar focal length is a
different class of instrument and worth saving for.
Galaxy imaging
At 500 mm, almost every galaxy is a smudge a few dozen pixels across. This telescope has no
business on small galaxies, and the sampling maths says so before the optics get a chance to.
Planetary imaging
Small aperture sets a low resolution ceiling, the short focal length means heavy amplification is
needed to reach a usable image scale, and the chromatic aberration you are amplifying is the one
thing you cannot process out. There is no configuration in which this is the right planetary tool.
Portability, setup and maintenance
Nothing to collimate, nothing to acclimate, nothing to clean beyond the occasional dust blow. It
lives in a small case, goes on a photo tripod head at a pinch, and is ready the moment it is
outside. Ownership costs nothing but the mount you have to buy separately.
Full specifications
Optics
Optics specifications for Sky-Watcher StarTravel 102 (OTA)
Aperture
102 mm (4")
Focal length
500 mm (19.7")
Focal ratio
f/4.9
Optical design
Air-spaced achromatic doublet
Type
Achromatic refractor
Glass / mirror
Crown and flint doublet, fully multi-coated
Resolving power
1.14"Calculated from aperture (Dawes limit), not a manufacturer figure.
Limiting magnitude
≈ 12Estimated from aperture under dark skies. Real skies are usually worse.
Imaging compatibility
Imaging compatibility specifications for Sky-Watcher StarTravel 102 (OTA)
Field correction built in
No
Usable visually
Yes
Corrector required
Yes — sold separately
Autoguiding
Recommended
Mount and tracking
Mount and tracking specifications for Sky-Watcher StarTravel 102 (OTA)
Mount included
No — optical tube only
Tracking
Depends on your mount
GoTo
Depends on your mount
Mounting interface
Vixen-style dovetail
Size and weight
Size and weight specifications for Sky-Watcher StarTravel 102 (OTA)
OTA weight
2.4 kg (5.3 lb)
Tube length
460 mm (18.1")
Tube diameter
115 mm
Longest transport dimension
560 mm (22")
Product
Product specifications for Sky-Watcher StarTravel 102 (OTA)
Brand
Sky-Watcher
Model
StarTravel 102
Status
Current
Price band
BudgetWe publish bands, not prices. Check the retailer for the current price.
Skill level
beginner
Editorial notes
Sold both as a bare optical tube and in package deals with alt-azimuth mounts. Specifications here describe the OTA only; check what a given listing actually includes.
Strengths and limitations
Strengths
+Very wide true field for the money — this is the cheapest way to frame a large open cluster properly.
+Light enough that almost any modest alt-azimuth mount will hold it steadily.
+Sealed optics that never need collimation and cool down almost instantly.
Limitations
−Visible violet fringing on the Moon, Venus, Jupiter and bright stars. This is inherent to a fast achromat, not a defect.
−At f/4.9 with no field flattener, stars smear towards the corners of any camera frame.
−Short focal length makes high magnification awkward and unrewarding.
Accessories
In the box
2-inch to 1.25-inch adapter
Tube rings and dovetail bar
Required, sold separately
An alt-azimuth or equatorial mount and tripod
A star diagonal
Eyepieces
Worth adding
A semi-apochromatic (fringe killer) filter to tame violet halos
A 2-inch wide-field eyepiece to use the full field
We list an accessory as included only when the product record says so explicitly. If a mount, eyepiece, camera, flattener, reducer, corrector, guider or adapter is not listed above, assume it is not in the box.