Sky watcher evostar 90 az3 90mm 35 f900 achromatic refractor telescope the sky watcher evostar series are two element air spaced multi coated object achromatic refractors they are truly outstanding high performance high resolution instruments manufactured to extremely high standards and mechanical precision with their long focal lengths and breathtaking optical performance they are ideal for the detailed high power study of the moon planetary surfaces and other objects in out sola