For observing Sun spots, transits of Mercury & Venus and Eclipses, very easy to use.
40 mm f4.5. Standard Solarscope. Optical specifications: focal length 13/9m, image quality better than one lambda (wavefront) Optical aperture: 40 mm, Sun's image size on the projection screen: diameter about 80mm. Observation screen size: 240 x 240 mm ². Dimension 410 x 370 x 260 mm, weight 750 g. Made in France.