Choosing a camera lens to create the bokeh effect.
Before you go out and buy lenses, it’s important to know which ones are recommended for bokeh photography. A shallow depth of field allows you to make a single object your point of focus, while everything distant from that focal point becomes blurred. Most lenses that allow for this have a low f-stop – a number referring to how wide open or closed the aperture of your camera lens is.
Think of the aperture like the pupil of your eye. The wider open it is, the more light it allows in – at the cost of depth of field. The narrower the aperture, the greater depth of field you’ll have on display – at the cost of bokeh effect.
The shape of the diaphragm blades in a lens also affects bokeh. Circular shaped blades create rounder out of focus highlights, while a lens with hexagonal blades reflects that shape in your imagery. Both can be effective – it all depends on your personal taste.