>The D800 has twice the pixel density of the D4. What are the >other features of the D4 that cause it to command a price >double that of the 800? Same question about the D3 - a little >more than twice the price of the 800 and a little less than >twice the pixel density. I've got both the D4 and the D800, and I end up using the D4 about 90% of the time, even for a lot of studio work, landscapes, and other things I thought where the D800 would dominate. Quite simply, the D4 can do virtually every thing the D800 can do, plus a whole lot more. Unless I were making huge prints and/or required 36MP, or had to have a small camera, it's been hard to find a reason not to use the D4. When you're using a tool to make your living (and the D4, in particular, is aimed at those buyers), it's all about which camera is best for the job, and not about cost. Each of these cameras were more than paid for on the first project I used them on.