Depth of field is the near to far sharpness in your pictures. A picture with shallow depth of field has only the main subject in focus, and everything in front of it and behind it is blurred. The opposite is a picture with deep depth of field, where everything is sharp from right up close […]
The adjustable hole in the lens diaphragm is created by a set of overlapping metal leaves, or ‘blades’. The greater the number of blades, the rounder the hole created and the better the lens’s ‘bokeh’ in out of focus areas. Aperture blades are often curved, too, to enhance that circular shape.