在OpenCV和Python的帮助下，您可以非常轻松地完成这项工作： 

    1. cap = cv2.VideoCapture(1) 
    2. # my webcam 
    3. cap.set(3, 1280) 
    4. # set the resolution 
    5. cap.set(4, 720) 
    6. cap.set(cv2.CAP_PROP_AUTOFOCUS, 0) 
    7. # turn the autofocus off

    我使用OpenCV 3.1.0-dev，Python 2.7.5和Logitech HD Pro网络摄像头C920

    ref
    https://oomake.com/question/339302