Focus stacking is the technique of capturing multiple frames at incrementally shifted focus positions and blending them in software to produce a final image with greater depth of field than any single frame can provide. At 1:1 magnification, where a single frame at f/8 yields approximately two millimeters of sharp depth, stacking fifteen to twenty frames at overlapping focus intervals produces an image where several centimeters are in acceptable focus. This is not achievable any other way.

The Sigma 28-45mm f/1.8 DG DN Art is a narrow-range zoom with an unusually wide maximum aperture for its category. f/1.8 across a zoom range is a specification that did not exist at a practical price and size before the large-diameter mirrorless mounts made the optical corrections feasible. The result is a zoom that behaves like a fast prime — subject separation, low-light capability, and rendering quality at maximum aperture — with the flexibility to shift perspective without changing lenses.