Wedge prism is an optical element with plane-inclined surfaces, usually the faces are inclined toward one another at a very small angles. It diverts light toward its thicker portion. Wedge prisms can be used as isolating components. Wedges may also be used to produce a small deviation which doesnt allow return to source.
A Neutral Density filter allows a photographer to control the exposure in an image very easily. The filter stops light reaching the camera sensor, therefore allowing us to leave the camera with a higher aperture for a longer amount of time.