AF Stop Button With the EOS 630/600, RT, A2/A2E/5, or 10 S /10 set to the AI Servo AF mode and continuous shooting, AF will not resume even after you let go of the AF stop button. Press the shutter release button halfway to resume AF.
We have defined the optical Nyquist frequency for a 4 K S 35 mm lens. It means that this lens needs to be able to pass through its entire optical system 80 black and white lines within every millimeter of the image size defined in Figure 1. To get a sense of the high demand of a 4K lens we show in Figure 2 below what 80 line pairs looks like.