A good 24-70mm f/2.8 lens is the workhorse of choice for a huge range of photographers and filmmakers, offering a versatile focal length range and a wide aperture suitable for a lot of uses and applications, though they are not always cheap. Sigma's 28-70mm f/2.8 DG DN Contemporary lens offers impressive image quality and performance in a small package and at quite an affordable price, and this great video review takes a look at just what you can expect from it.