It might seem like full frame users get all the fun lenses, but APS-C shooters still make up a large portion of photographers. And while they can often use certain full frame lenses, having options made for specifically APS-C can save on size, weight, and price, often quite significantly. Sigma's new 18-50mm f/2.8 DC DN Contemporary lens is made specifically for APS-C users, and this excellent video review takes a look at the performance and image quality you can expect from it.