Focus Stacking
Focus stacking is a computational photography technique that combines multiple images taken at different focal distances to produce a single photograph with greater overall sharpness than any individual shot. This method addresses the fundamental optical constraint where increasing depth of field by stopping down the aperture often leads to diffraction, which degrades image quality. By capturing the scene in multiple exposures, photographers can maintain optimal aperture settings for sharpness while ensuring that both foreground and background elements remain in focus.
The process typically begins with the photographer taking a series of shots, shifting the focus point incrementally from the nearest to the farthest part of the subject. These images are then aligned and merged using specialized software, which selects the sharpest pixels from each frame to construct the final composite image. This approach is particularly valuable in macro photography and landscape photography, where the depth of field is naturally shallow or where extreme depth of field is required without sacrificing resolution.
While effective, the technique requires careful execution to avoid artifacts such as ghosting, which occurs when subjects move between exposures. It is generally unsuitable for scenes with moving elements, such as flowing water or wind-blown foliage, unless the movement is minimal or the exposure times are extremely short. Consequently, focus stacking is most commonly applied to static subjects where maximum detail retention is prioritized over the speed of capture.