The Nikon system of digital single-lens reflex (SLR) bodies and lenses is a popular choice among serious photographers worldwide. This page makes it easy to shop for Nikon digital bodies and Nikkor lenses. Every component manufactured by Nikon is covered, plus a few exceptionally good third-party components. If you are new to photography, you might want to start with my article "Building a Digital SLR System".
This article goes through every section of the Nikon system and concludes with some starter system recommendations.
Sigma makes some interesting lenses for digital SLR cameras. They also produce some of their own digital SLR bodies with a class-unto-itself new type of sensor. Sigma is mainly known as a third-party lens manufacturer, producing lenses in mounts compatible with the major brands: Canon, Nikon, Pentax, Sony, Olympus. They offer high-quality glass in many of the popular focal lengths which, in many cases, are at more affordable prices than the specific manufacturer’s offerings.
This article covers every current Sigma product.