Depth of field (DOF) or focus range is a feature of optical systems with a specific configuration. It refers to the spatial or distance range that the configuration allows to remain sharp or focused. A high DOF in an optic system is desirable in microscopy and macro photography, among other applications. A solution to a limited DOF in an optical system is to take a sequence of images with different focal distances and subsequently fuse those images into one that is completely focused. This process is known as multi-focus image fusion (MFIF). The literature on MFIF techniques is extensive and of current interest in the scientific community of image fusion. In contrast, literature about the complete MFIF process is scarce. This paper aims to propose a general method of MFIF, which begins with configuration and calibration of optical system, followed by the implementation of a fusion technique, and ending with the visualization of the fused image. For this study, we used a low-cost optical system with a variable DOF in the range [0.18 m, ∞]. The proposed method is directly applicable for acquisition systems with different optical configurations.