1/250th shutter speed is fast,
1/30th shutter speed is slow.
Shutter speed - how fast the shutter opens and closes to let the light into the camera.
Aperature - How big the opening of the lens is to let the light in.
You physically cant take a photo at 1/20th without a tripod.
Aperature is usually expressed in F-numbers.
F2.1 is large
F22 is small.
