How does focus stacking work, and when should I use it instead of a small aperture?

Focus stacking captures multiple exposures of the same scene at different focus distances, then combines the sharpest region of each frame into a single composite image with far more total sharp depth than any single exposure could achieve — the standard technique for scenes where the aperture narrow enough to cover the needed depth of field would push well into diffraction-limited softness instead.

Why Stacking Beats Stopping Down at Extreme Close Range

At true macro magnification, total depth of field can be a couple of millimeters even at f/8, and reaching enough depth of field through aperture alone would require stopping down far past where diffraction starts degrading the whole frame. Focus stacking sidesteps this entirely — each individual frame stays at a reasonably wide, diffraction-safe aperture, and the combined result covers far more depth than a single frame at any aperture could, without the softness a single extremely narrow aperture would introduce.

When to Reach for Stacking Instead of a Narrow Aperture

A single narrow aperture remains the simpler, faster option whenever it can cover the needed depth of field without crossing into visible diffraction softness — check your actual hyperfocal distance and near limit before assuming you need to stack. Stacking becomes the better tool specifically at macro distances, or in landscape work with an unusually close foreground element that a wide-angle lens's own hyperfocal distance can't reach even at a diffraction-safe aperture, and in any static-subject scene where the extra capture and processing time genuinely pays off.

Check whether a single aperture can already cover your scene before reaching for a stack, in the DoF & Hyperfocal Calculator.