How to change the flash box of Shenniu into a constantly lit fill light? Or is there anything that can make the external flash flash when the phone takes pictures?

Some flashlights provide the function of continuous illumination and supplementary light, but usually the power is not large and the brightness is not high enough, so it makes no sense to put them in a light box. So, there is no good way. You can only buy another set of lights that are always on and change the flash. If you like magic cows, you can continue to buy magic cows, such as sl series LED lights, light boxes and shelves, which can be used continuously.

On the issue of using the mobile phone flash, you use the magic cow flash system, so you can use the magic cow mobile phone flash directly to flash.