Why is Apple's 6-shot ppt not very clear?

When we usually shoot a computer screen with a mobile phone, we will always find some "water ripples" that affect the picture. So how did these "water ripples" come from? How can we destroy it?

In fact, these "water ripples" are caused by the screen refresh frequency being lower than the shutter speed of the mobile phone. The refresh frequency is what we often call the Hertz (hz) of the screen. The refresh frequency of our old TV set is generally 50hz, and the new one is 60hz. Most LCD monitors we use now are 60hz by default.

Because the screen doesn't always shine, but it will be refreshed every once in a while. For example, 50hz means that it is refreshed 50 times per second, and the naked eye is completely unaware of what is flashing on the screen. When a mobile phone shoots a screen, most of them will also have a faster shutter speed. When the shutter speed is faster than the refresh frequency, we can capture the screen refresh process invisible to the naked eye, which will produce "water ripples"

To eliminate water ripples, it is actually very simple, that is, slow down the shutter speed. If you use a SLR or M-class digital camera, you can control the water ripple by adjusting the shutter speed. But on mobile phones, most mobile phones don't support adjusting the shutter speed. Therefore, it is really difficult to take pictures without waterline when the mobile phone takes a screen. Now some mobile phones will have an option of "reducing flicker", and there will be 50hz, 60hz or automatic setting adjustment. This setting is specially added for this situation, but the effect is not too obvious. Therefore, when shooting pictures, you can only put up with water ripples by yourself, or pray that the "flicker reduction" in the mobile phone will play a role.