1) More power. A key and immediate advantage of using a speedlight rather than built-in flash is a huge increase in power. ... Using a camera's built-in flash can be pretty sluggish, but a flashgun has much faster recycle times so you're less likely to miss a moment.
Is a Speedlite necessary?
An on-camera flash, also known brand-wise as a “speedlight” or “speedlite,” is an indispensible accessory for many photographers; it provides additional light when conditions become too dark to handhold your camera comfortably, allows you to achieve more balanced exposures in daylight, permits freezing of fast-moving ...
When should I use Speedlight flash?
Most people use flash photography only when it's dark, at night or indoors. This is because there isn't enough natural light or ambient light. But there are many other situations where we recommend it. You can use a flash to get rid of shadows from your photo.