3. Diffraction

While closing down the diaphragm to create a smaller aperture increases depth of field it also increases the impact of diffraction which softens the image.
Diffraction is the bending of light rays as they pass over the edge of the aperture blades.
These rays don’t converge on the sensor surface and consequently they give a soft image.

The smaller the aperture, the fewer the number of light rays passing through and the greater the proportion of rays being bent.
As a general rule, it’s advisable to not close down a lens aperture to the smallest value available.

                                                                                                                                           NEXT>>