Top performing optics

Without doubt the stand-out feature of the SD103S telescope is its optical performance. Basic refractors suffer from chromatic aberration; this is when short, mid and long wavelengths of visible light appear to reach slightly different focus positions, and cause colour fringing, an effect most visible on the sharp edges of bright objects such as the Moon. The SD103S uses a 103mm diameter doublet lens to reduce this effect. Further improvements occur through the use of FPL-53 glass, a material highly regarded for its low dispersion of different light wavelengths, and which on its own is able to keep chromatic aberration low. The use of this high-performance optical glass is where the ‘SD’ (Super extra-low Dispersion) comes from in the telescope’s name. As a result the SD103S produces stunning, high-contrast views. Diffuse objects such as the Orion and Dumbbell Nebulae are extremely clear, star clusters are vibrant and the shapes of galaxies such as Bode’s Galaxy, M81, and the Cigar Galaxy, M82, are easy to make out.