Orion EON 115mm ED triplet APO refractor

ED glasses are fast becoming ubiquitous in astronomical equipment, particularly in banishing the remnants of chromatic aberration of the classic refractor. Steve Ringwood takes a look at a 115mm (4.5″) f/7 air-spaced triplet from Orion in the USA. Designed for both visual use and astrophotography, it sports a beefy three-inch dual-speed Crayford focuser and comes supplied its own hard carry case.