Good news and bad news.
The good news is that you probably already have a flash unit for your camera.
The bad news is that it probably won’t work.
Why?
Remember that to fill the frame we have to have our lens almost touching the subject. This
means that the angle of the - on camera - flash is such that it won’t hit the subject. You are just
too close.
You are going to have to get the flash off the camera so that you can use it at a better angle. One
where the light has a chance of hitting the subject.
One way – not the best – is to uses a bracket of some sort so that while the light is still attached
to the camera it is off to the side. Then you can swivel the lights’ head so that it is aimed at the
subject.