T-threads onto which extension tubes and 1.2-inch adaptors are attached. Removing an extension tube allows a T-threaded camera to be connected directly to the diagonal.
The views through the scope were impressive. The Double Cluster in Perseus, NGC 869 and NGC 884, appeared bright and vibrant with good colour definition. A view of the Orion Nebula, M42, showed lots of detail. The faint outer regions were also beautifully revealed by the scope’s high-contrast optics. It was a real pleasure to view this object through the SD103S.
A brighter test view of the Moon showed the apochromatic optics of the SD103S to be true to form, and no colour fringing was seen at any point around the Moon’s limb. Using a 5mm Vixen eyepiece (not included) delivered a very comfortable view of the lunar surface with features as small as 10km visible under really quite unsteady conditions.
Similarly, imaging with a camera attached was a pleasurable, stress-free experience. The focuser is responsive and excellent at holding position. It was lovely to image with such a bright, high-contrast field of view. On a less positive note, bright stars exhibit a diffraction pattern, which appears to originate from the clips used to hold the objective in place. In addition, large sensor images do show some optical distortion of stars towards the corners of the imaging frame. An optional matching Vixen reducer/field-flattener goes some way to alleviating the distortions, but in our experience didn’t fully eliminate them. Despite this, approximately 85 per cent of the inner frame still produced a great image.
The Vixen SD103S is a strong performer both visually and photographically. Its portability is another factor in its favour too. Consequently, this is a no-fuss instrument that is capable of delivering excellent results.