I am a starting assistant photographer. And I need to buy my own camera and lens. I have a Canon XTI now, but I dont think that this camera is the quailty that I need. I would like advice on what camera and lens will best fit my needs??? My Photos will be of People, wildlife, nature, landscapes. I would like the camera to have a dpi level of at least 300 or be adjustable Dpi. It can be nikon or canon. Any help would be great!!!