Top per­form­ing op­tics

Sky at Night Magazine - - FIRST LIGHT -

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.

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