All of the following images can be found on the homepage of mine and my wife's photography website, kentandcarolynphotos.com.
(This does not include the image of the lens itself.)
I've chosen these images specifically because of the lens they were taken with.
The Sigma 70-200mm f/2.8 
The fact that it's a Sigma is not very important, in my opinion. To me, it's the 150-200mm range of the lens, due to it's ability to create such a razor-thin depth of field when used in combination with a 2.8 f-stop.
And it makes for some amazing portraits. 
