doublet achromatic objective lenses,additional focus reducer for super achromatic optical system,better optical performance for 6 achromatic refractor telescope - doublet achromatic objective lenses,additionalfocus reducer for super achromatic optical system.there are two kinds of specification - 6inch, 5inch.Aperture:6inch/152mm telescope lens,Focal length (f):760mm (30-inch), f/5,Multi coated ...
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