I recently received my new lens. I originally was looking for a semi-pro grade long distance zoom in the 100-300mm range. However, after thinking about it, since most of my shots are either landscape or portrait type shots, a lens in the 18-70mm range would suit most of my needs. So after doing extensive research and comparing raw data, I selected the Sigma 18-50mm f/2.8 EX DC Macro HSM. The HSM is required with my D40 in order to autofocus.
I have had the lens for 24 hours and have probably taken 100 photos with it already, and I am very impressed. This Sigma lens' zoom operforms way better than the Quantaray zoom I reviewed earlier. However, that is to be expected. The Quantaray was a bargain basement lens, and this is Sigma's high end EX model. The autofocus is very fast and spot on everytime. It consists of 15 lens elements, 4 of which are extremely low dispersion lenses. This means that there is very little color loss or chromatic aberration with this lens throughout the zoom range. Also, it is a constant f/2.8 lens, which allows for excellent low lighting photos and excellent bokeh. It is also a very sharp lens and provides excellent contrast. The build quality is fantastic, and feels very heavy and well built.
Not only does this lens perform well for landscapes and portraits, but the macro function is very useful. It has a minimum focus distance of 7 inches, but I believe that is from the rear of the lens. Since I have held the lens less than 3 inches from my subject and it focuses dead on every time. This will allow me to experiment with my fly photography in the coming weeks. Here are a couple sample shots from the past few days.
I am very pleased with this lens and recommend it to anyone wanting to upgrade from the kit lens into a semi-professional quality lens for less than $400. When comparing this lens to it's Nikon counterpart, it provides similar performance for 1/3 the cost.