1. defocus - Noun
2. defocus - Verb
defocus (third-person singular simple present defocuses or defocusses, present participle defocusing or defocussing, simple past and past participle defocused or defocussed)
(transitive) To cause (a lens, or a beam of light or particles, etc.) to be out of focus.
The process of going out of focus.
(optics) The distance by which the focal point is in front of (positive defocus) or beyond (negative defocus) the image or target surface.
Source: en.wiktionary.orgAt the DOF limits, however, further stopping down decreases the size of the defocus blur spot, and the overall sharpness may still increase. Source: Internet
Determining combined defocus and diffraction Hansma (1996) and Peterson (1996) have discussed determining the combined effects of defocus and diffraction using a root-square combination of the individual blur spots. Source: Internet
Eventually, the defocus blur spot becomes negligibly small, and further stopping down serves only to decrease sharpness even at DOF limits (Gibson 1975, 64). Source: Internet
Optically, as a lens is stopped down, the defocus blur at the Depth of Field (DOF) limits decreases but diffraction blur increases. Source: Internet
Optimal f -number seeAlso As a lens is stopped down, the defocus blur at the DOF limits decreases but diffraction blur increases. Source: Internet
The increase of the circle diameter with defocus is gradual, so the limits of depth of field are not hard boundaries between sharp and unsharp. Source: Internet