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Sky-Watcher Star Discovery 150P Go-To reflector

A beginners’ Go-To telescope that is accurate and versatile. See an interactive 360° model of this scope

Our rating 
4.0 out of 5 star rating 4.0
Price correct at time of review
Sky-Watcher Star Discovery 150P full header

The market for beginners’ telescopes is still going strong, thanks in part to programmes such as The Sky at Night, Stargazing LIVE and the recent revamp of Cosmos.


Demand gives impetus to telescope makers to come up with new products, and Sky-Watcher is certainly keeping pace with its Star Discovery 150P, a 6-inch Newtonian reflector on an altaz Go-To single arm mount.

It is supplied with a tripod, a basic red-dot finder, two 1.25-inch eyepieces (25mm and 10mm) and a 1.25-inch 2x Barlow lens, which is threaded so that you can attach a camera.

The mount has a battery compartment that takes eight AA batteries, as well as a port for an alternative power supply such as a power tank.

Also on the mount is a connection for the handset and a ‘snap’ port for camera control: you could dispense with the telescope entirely, replacing it with a DSLR mounted on a camera bracket to record landscape or timelapse images.

The handset packaged with the Star Discovery 150P is the SynScan V4, which is slightly larger and a little more bulky than the more prevalent SynScan V3, though the arrangement and function of the control buttons are identical to previous versions.

It offers a rich variety of targets, with nearly 43,000 objects in its database.

There are two alignment routines to choose from, brightest star and two star.

The first method divides the sky into zones (north, south and so on) and suggests stars to use for alignment in the zone you’ve chosen.

The second allows you to choose any stars in the sky.

Both resulted in good slewing, with targets usually placed in the central 50 per cent of the view in the 25mm eyepiece.

This telescope features in our list of the best telescopes for kids

Travelling through the sky

Using the same eyepiece, we aimed at Aldebaran in Taurus to test the quality of the field of view: we were pleased to find that the star appeared pin sharp across 75% of the view with only a little coma showing up towards the field edges.

The Star Discovery 150P has a focal length of 750mm, giving the system a focal ratio of f/5.

Therefore the 25mm and 10mm eyepieces give magnifications of 30x and 75x respectively – a nice range for a beginners’ scope and one that doesn’t push the optics too much.

The 25mm eyepiece provided a wide field of view that allowed us to take in the whole of the Pleiades and almost all of the Sword of Orion.

The 10mm gave a good increase in magnification and in moments of steady seeing we were able to glimpse the two fainter components of the Trapezium Cluster, which sits at the heart of the Orion Nebula.

By combining the 10mm eyepiece and 2x Barlow, we were also able to split tight double and multiple stars – including triple star Iota Cassiopeiae, where the closest companion is only two arcseconds away from the primary star.

Using the 25mm eyepiece we could fit both members of galaxy pair M81 and M82 into the view, with the 10mm revealing a mottled edge on disc of the latter.

The Crab Nebula, M1 in Taurus, was visible as a small patch of mist, while star clusters such as M44 in Cancer and M35 in Gemini appeared to sparkle against a black backdrop.

Although not designed for astrophotography, we were able to attach both an iPhone and a DSLR to the telescope (using our own adaptors) to capture a few shots of the Moon.

With the DSLR we also had to use the Barlow lens in order to achieve focus, but overall we were pleased with the basic lunar images taken with the setup.

We found this an easy system to set up and use.

It will give beginners a lot of fun discovering the wonders of the night sky.

Tracking was generally good, with targets remaining close to the centre of the view for up to 20 minutes and only a small amount of drifting.


Sky-Watcher has also incorporated its ‘Freedom Find’ technology into the mount, allowing you to swing it in either axis without it losing alignment, making it quite a versatile instrument.

Freedom to explore

One of the technologies that Sky-Watcher originally developed for its more sophisticated mounts – but is now appearing in its more basic products such as the Star Discovery 150P – is Freedom Find. By making use of dual axis digital encoders, the mount can be physically moved in either or both axes to point to a different part of the sky, yet the mount will know where it is pointing. This is something that Sky-Watcher’s previous mounts were unable to do.

We tested this freedom by first performing a star alignment and then using the handset to slew to the bright star Rigel in Orion. At the time of review, comet 2014 Q2 Lovejoy was to the lower right of this star, several degrees away, so we manually rotated the telescope to it. We then used the handset to return to Rigel, which it duly did. We performed similar tests in other parts of the sky with the same result, showing that the encoders do indeed do their job.

Single arm fork mount

The mount is sturdy and easily attached to the tripod via three bolts. There are ports for the hand controller and power from an external power tank, as well as a camera ‘snap’ port. The mount also features a battery compartment that can take eight AA batteries.

Eyepieces and Barlow lens

Two eyepieces (25mm and 10mm) and a 2x Barlow lens are supplied. The 25mm gave good wide-field views of objects such as the Sword of Orion, while the 10mm provided extra magnification for closer study. The Barlow was particularly useful for splitting close double and multiple stars.

Hand controller

The hand controller supplied is the SynScan V4, which is a little larger than the SynScan V3 but possesses the same arrangement of buttons. It has a database of 42,900 objects, including the Messier, IC, NGC and Caldwell catalogues, as well as planets, named stars, double stars and variable stars.


The stainless steel tripod is sturdy and can easily hold the combined weight of the mount and telescope. It can be adjusted for height and provides a good platform for the rest of the telescope to operate. It also includes a useful eyepiece tray.


The parabolic 6-inch primary mirror has a focal length of 750mm, giving a focal ratio of f/5. Views were good, with pin-sharp stars visible across the central 75 per cent of the field of view through the supplied 25mm eyepiece, though there was some coma towards the field edges.

Vital stats

Price: £399.00
Aperture: 150mm (6 inches)
Focal Length: 750mm (f/5)
Mount: Computerised single fork arm altaz
Weight: 18kg
Supplier: Optical Vision
Telephone: 01359 244200

This review originally appeared in the March 2015 issue of BBC Sky at Night Magazine.