For me it is the basic standard lens. Its aperture of 2.8 can easily play with depth of field and get out in almost all situations (there then remains the 50mm f1.4). Its focal length is ideal for all kinds of images (portrait, landscape, proxi etc.).
The build quality is very good, then his dive. This goal is no exception to the rule, its best dive is about 2 diaph above its maximum aperture is f / 5.6, f / 8. Rings pleasant to handle.
