SV135 fully multi-coated zoom plossl eyepiece zooms to any focal length between 7 mm and 21 mm - pick the better magnification for your subject. As a beginner; SV135 zoom eyepiece is good for starter astronomer!7mm-21mm linear continuous zoom.The SV135 is stiff enough not to accidentally change focus and smooth enough to rotate without having to hold the eyepiece base with your other hand. 7-21mm which will give you a wide range of magnification options.The SVBONY 2" uv ir cut block filter is required for all digital imaging with digital cameras; CCD cameras and an improved webcam; the UV-IR-Cut filter uses the latest coating technology to provide the great filter quality-and use lifetime; with a DSLR camera; CCD camera or telescope.