... optical system,better optical performance for 6 achromatic refractor telescope - doublet achromatic objective lenses,additionalfocus reducer for super ... system for EQ5,GPS telescopes:GPS external module,astrophotography telescope:Electro-focuser compatible with Auto GOTO tracking starsystem , ... 1000mm,4inch,D=102mm,f=660mm.other ED APO refractor telescope:3.15inch,D=80mm,f=480mm,4inch,D=102mm,f=700mm ...