6-inch dou­blet lens

Sky at Night Magazine - - OCTOBER / FIRST LIGHT -

Aper­ture is king, they say, and at six inches in di­am­e­ter the Evostar 150ED DS-Pro likely presents the max­i­mum man­age­able size of re­frac­tor for many ama­teurs. The dou­blet lens is mul­ti­coated and dis­plays a pur­plish hue. Pho­to­graphic tests showed no sign of un­wanted re­flec­tions or arte­facts, and vis­ual star tests demon­strate that the lens cell holds the glass with­out ev­i­dence of skew­ing or pinch­ing, even through tem­per­a­ture drops of over 10°C. The large aper­ture makes find­ing fainter ob­jects eas­ier, and even with moon­lit skies and mod­er­ate light pol­lu­tion we could ob­serve both ma­jor sec­tions of the Veil Ne­bula com­plex with our OIII fil­ter and 21mm eyepiece. Mean­while, plan­e­tary neb­u­lae such as M57 and M27 stood out re­ally well from the back­ground sky. Glob­u­lar and open clus­ters were sharp and clear, and bright star Vega showed only the faintest trace of false colour as the see­ing var­ied. Lu­nar views dur­ing steady see­ing showed good de­tail in crater walls and we eas­ily picked out the main crater­lets within the crater Plato.

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