Sigma DG 120-400mm f4.5-5.6 APO HSM OS for Nikon FThe Sigma DG 120 400mm f4. 5 5. 6 APO HSM OS is a long lens with a long name. This is a long range supertelephoto zoom lens with pretty solid performance. The optical image stabilizer helps keep things steady, and a large grip tripod foot makes for easy handling. In excellent condition, with only minor cosmetic wear, clean glass, and good function. For Nikon F mount SLR cameras.