can anyone advice what does speedlite used for how do i know which to buy?
i am aiming for 1 but do not know how it works and which should i buy.
can any professional advice me on this.
thank you.
Sorry, I'm not a professional, but I can answer your question.
A speedlight is very useful in certain situations, for instance; outdoors in daylight it is used for "fill" light to lighten shadows.
Indoors, you can use it to provide enough light for hand-held shots. By adding enough light, you can minimize blur caused by camera movement.
A speedlight uses batteries, so you can take it practically anywhere that flash photography is allowed.
I use a Nikon SB-910 which I can recommend with enthusiasm. The Nikon Speedlight is capable of i-TTL which works with a (Nikon) camera to adjust the light automatically, which is handy for quick snapshots in an informal setting.
The flash (any speedlight) should be modified by one or more actions, such as; bouncing the light from a nearby white surface, or by getting the flash some distance from the lens, or placing a diffuser between the flash and your subject.
If you can afford it, get a modern speedlight that works with your system.