理论在这里: http://www.worth1000.com/tutorials/162260/theory-depth-of-field "The DoF being the same in both cases may only really be relevant in technical applications. Most of us here are concerned about the visual impact of the image. If you want to isolate your subject visually from the background, a longer focal length does work better in most circumstances because it will show a smaller portion of the background."
【在 e**n 的大作中提到】 : 理论在这里: : http://www.worth1000.com/tutorials/162260/theory-depth-of-field : "The DoF being the same in both cases may only really be relevant in : technical applications. Most of us here are concerned about the visual : impact of the image. If you want to isolate your subject visually from the : background, a longer focal length does work better in most circumstances : because it will show a smaller portion of the background."