Steven Bumgardner likes beautiful landscape photography just as much as the next guy, but having worked in National Parks for 20 years, he also thinks it's important to look at the impact humans have on the environments they visit. Yosemite receives more than 3.5 million visitors a year and most of them spend the bulk of their time in a seven mile long stretch called Yosemite Valley. In other words, it's kind of a crowded place. You wouldn't think it from looking at the pictures, but as this video shows, in all the majestic imagery that comes out of places like Yosemite, there are probably scores of people standing right behind the camera, just out of frame.