I have a Nikon D40 and the body is great but of course the cheap-o lens it came with broke within the first few months. I am looking to get a new lens, a better one to fit my needs. I do alot of event photography for a side job and sometimes need to pull in shots from far distances. I also love to do closeup portraits. This is my first digital SLR so im kind of in the dark about what to get as far as lenses. Any thoguhts? Ive been looking at the Sigma 70-300mm lens. Will this do the job?