The Sky-Watcher 4″ (120mm) f/5 BK1206AZ3 refractor

The Sky-Watcher 4" (120mm) f/5 telescope falls in to the category of an achromatic refractor that gives good resolution in a neat, portable package.

The telescope gives fine astronomical vistas and close focus views of stars, galaxies, clusters, nebulae, planets, and the moon. With correct projection or filtering viewing the sun is also possible.

The BK1206AZ3 is a great terrestrial telescope for alt-azimuth or tripod mounting. A competitive price with good imaging makes this a good entry-level beginner's telescope with the bonus of easy handling makes the BK1206AZ3 a good travelling companion for a seasoned sky watcher.

The BK1206AZ3 has many similarities with smaller brother, a 80mm f/5 refractor. With a larger aperture, this model has a better capacity for collecting light at the same focal ratio and gives excellent wider field views.

Weighing only 3kg (6.5lbs) and measuring about 50cm (21.7") this is a very portable telescope.

As a refractor, set up is straightforward and takes only a few minutes. Minimal maintenance is needed as the optics are enclosed and factory collimated.

Mounting the telescope on alt-azimuth or equatorial mounts is quick and simple.

This telescope also has excellent performance as a fixed aperture, 510mm lens for astrophotography. The f/5 focal length combined with a digital SLR camera on a fast setting can capture excellent astrophotography. The telescope is equally at home taking terrestrial nature images.

An unshakeable equatorial mount and guidance system are needed for astrophotography.

A T-mount thread on the eyepiece holder allows direct attachment of an SLR camera and the optional 2.5" (60mm) extension tube allows close focus standard photography options.

The Sky-Watcher 4" (120mm) f/5 is recommended for urban astronomy – with a 13.1 stellar magnitude and 240x highest practical power.

The makers also recommend as an accessory a single axis EQ5 battery motor drive with hand controller that gives tracking 2x and 8x tracking speeds.

All in all, this refractor packs a punchy performance for a relatively low outlay against other models in the same class and is a great introduction to astronomy for a new observer or a competent and robust back up for a more experienced user.