apo refractor
A small-aperture scope that delivers great views
Acar emblazoned with the words ‘Gran Turismo’ evokes an expectation of performance and luxury. William Optics has produced a compact, 2.8-inch apochromatic refractor that hints at the motoring connotations with its name, the GT71. Lifting the bonnet – or in this case the lens cap– reveals that ‘Gran Turismo’ is discreetly etched onto the lens cell. We were keen to discover whether this little telescope lived up to those big ideals.
The GT71 certainly has luxurious looks, with its gold trim and classic white tube delivering an impression of sophistication. There is something about the fit and finish of this new model too that just feels ‘right’. What really matters, though, is the performance, and to test this our review telescope was supplied with an optional field flattening and reducing lens, the William Optics Flattener 6A adaptor. This has a dedicated spacing ring for the GT71 and Canon EOS fittings, and we attached our DSLR camera directly to this. It’s a very quick and straightforward method of using a camera with the telescope. You just focus and go.
Finding the perfect balance point on a mount can be tricky for little refractors with short dovetails, as there is limited room to position the tube rings, but the lightweight GT71 should be usable with a wide range of mounts, including the popular travel-friendly type. Indeed, with its soft travel case and compact size, only 325mm when the dew shield is retracted, this seems an ideal companion telescope for travelling astronomers.
Optical excellence
Our first targets were the bright stars in the constellation of Orion. These large, hot, blue stars will often highlight any optical issues, but we were pleased to see that the triplet lens system showed no evidence of star bloating or unwanted reflection artefacts, demonstrating good colour correction and star shapes across the picture.
During use the focuser was solid and dependable, and held our heaviest camera firmly without flexing when fully extended. We liked the large easy to handle coarse focusing knobs and the slick operation for fine focusing, but remain unconvinced of the usefulness of the thermometer that is included on one side.
Swapping our DSLR for a colour CCD, we were able to capture images of large targets, such as
SKY SAYS… The lightweight GT71 should be usable with a range of mounts, including the popular travelfriendly type