As refractor, the objective diameter is up to 152mm/6, 127mm/5 and 102mm/4 but with less chromatic aberration and extra low dispersion and at reasonalbe price. Perfect for the serious terrestrial observer, also for the veteran astronomer. Objective foucs length: 1200mm Objective diameter: 152MM Multi Coated ST2 CYLINDRICAL STEEL TRIPOD EQ5 EQUATORIAL MOUNT 8X50 VIEWFINDER EYEPIECE: 31.7MM PL6.5/PL20 50.8MM foucser tube 31.7mm 90 degree diagonal