Methods and systems to focus an imager for machine vision applications are disclosed. A disclosed example machine vision method includes: capturing, via an imaging assembly, an image of an indicia appearing within a field of view (FOV) of the imaging assembly; recognizing, via a controller, the indicia as a focus adjustment trigger, the focus adjustment trigger operative to trigger an adjustment of at least one focus parameter associated with the imaging assembly; adjusting the at least one focus parameter based at least in part on the indicia; locking the at least one focus parameter such that the at least one focus parameter remains unaltered for a duration; and responsive to the locking of the at least one focus parameter, capturing, via the imaging assembly, at least one subsequent image of an object of interest.