Sigma 56mm F1.4 DC DN C is an Auto Focus (AF) Standard Prime lens with APS-C / DX max sensor coverage. When mounted on a APS-C / DX sensor camera, it will give you an FF equivalent focal range of 84mm. Providing a max aperture of f1.4 at 56mm, this lens is very fast.
Sigma 56mm F1.4 DC DN C is weather sealed which makes it an ideal lens for outdoor use, especially when coupled with a weather sealed camera body.