A method for operating an image acquisition system to provide an image that is relatively free of an effect of longitudinal chromatic aberration in one or more lenses of the image acquisition system, the image acquisition system comprising an imaging system including a variable focal length lens, an illumination system, and a controller, the method comprising: operating the variable focal length lens to periodically modulate a focus position of the imaging system over a plurality of focus positions along a Z-height direction; providing a first wavelength image exposure contribution by operating the illumination system to provide an instance of strobed illumination of a first wavelength timed to correspond with a first phase timing of the periodically modulated focus position which focuses the first wavelength image exposure contribution at a first focus plane; providing a second wavelength image exposure contribution by operating the illumination system to provide an instance of strobed illumination of a second wavelength timed to correspond with a second phase timing of the periodically modulated focus position which compensates for longitudinal chromatic aberration of at least the variable focal length lens and focuses the second wavelength image exposure contribution at the first focus plane, wherein the second wavelength is different from the first wavelength and the second phase timing occurs after the first phase timing; and providing a wavelength combining image that is relatively free of the effect of longitudinal chromatic aberration by combining the first and second wavelength image exposure contributions, wherein the combining of the first and second wavelength image exposure contributions to provide the wavelength combining image comprises providing both the first and second wavelength image exposure contributions during a single image integration period of a detector of the imaging system. operating the variable focal length lens to periodically modulate a focus position of the imaging system over a plurality of focus positions along a Z-height direction; providing a first wavelength image exposure contribution by operating the illumination system to provide an instance of strobed illumination of a first wavelength timed to correspond with a first phase timing of the periodically modulated focus position which focuses the first wavelength image exposure contribution at a first focus plane; providing a second wavelength image exposure contribution by operating the illumination system to provide an instance of strobed illumination of a second wavelength timed to correspond with a second phase timing of the periodically modulated focus position which compensates for longitudinal chromatic aberration of at least the variable focal length lens and focuses the second wavelength image exposure contribution at the first focus plane, wherein the second wavelength is different from the first wavelength and the second phase timing occurs after the first phase timing; and providing a wavelength combining image that is relatively free of the effect of longitudinal chromatic aberration by combining the first and second wavelength image exposure contributions, wherein the combining of the first and second wavelength image exposure contributions to provide the wavelength combining image comprises providing both the first and second wavelength image exposure contributions during a single image integration period of a detector of the imaging system.