The Nikon D3 is currently the flagship Nikon DSLR. It represents the entrance of Nikon in the full-frame market where Canon was the sole runner for the last several years. Soon, Sony will join with its first full-frame DSLR. This is definitely a high-end and uncrowded market. Canon has 2 1/3 models there, with their flagship EOS 1Ds Mark III, the not-quite-full-frame EOS 1D Mark III and the completely full-frame EOS 5D Mark II. Nikon has the D3 and its smaller sibling, the D700. Sony launched its Alpha A900. The Nikon D3 is currently available from Amazon.
A full-frame DSLR is one where the sensor is the size of standard 35mm film. This is 1.5X larger and wider than most DSLR which equals 2.25X more surface area. The effects of having a larger sensor are twofold. One is that legacy 35mm lenses capture the same angle-of-view on a full-frame DSLR as they did on a 35mm film SLR. The other is that sensor makers have more area to work with. With extra area, manufacturers can make larger more sensitive photosites (single-color pixels) or pack more of them. Nikon has chosen the former approach. The result is that the D3 and D700 have the same 12 megapixels resolution as the cropped-sensor D300 but these full-frame digital cameras can capture images at ultra high-ISO up to 25600. This is a full 3 stops higher than nearly all DSLRs. Canon and Sony have taken the latter approach, producing 21 and 25 megapixels cameras respectively. The Nikon approach favors low-light action-freezing photography while the other approach favors larger prints.
Due to their approach to full-frame, Nikon produces the cleanest high-ISO images of any current DSLR cameras. Take a look at the unmodified 100%-scale crops below to see how the D3 performs at each ISO setting:
Amazingly, image noise only becomes intrusive at ISO 6400. Still, ISO 6400 on the D3 is usable for mid-size prints and ISO 12800 is usuable for small prints. This is truly class-leading performance shared between the Nikon D3 and D700. If there is one factor for which the D3 excels above all else, it is its high-ISO performance. Read the hands-on review at Neocamera or buy the Nikon D3 from Amazon.