Planar T* 28mm F2.8 is truly compact, just 50mm from mount rear to front tip, and lightweight, a mere 9.9 ozs. This wideangle lens offers high center contrast even with the aperture fully opened. It's a sure winner in terms of cost performance too. Lens construction: 7 elements in 7 groups Angular field: 74 degrees Minimum focus: 10 inches. Aperture range: F/2.8 - 22 Diaphragm action: fully automatic. Filter size: 55mm. Optional lens hood: 55mm G-12 soft or No. 1 metal w/ 55-86 ring. Weight: 9.9 oz