Steve Ringwood reviews a dedicated 3″ field flattener designed for use with Orion’s EON 115/130 EDT refractors. One side of the field flattener threads on to the 3″ focuser, whilst the other offers a wide M48 thread that enables fixture of DSLRs, etc. without the vignetting possible with smaller M42 designs — particularly when deployed with full frame sensors.
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.