Combining or ‘stacking’ a group of similar images is a common photography technique. Which is why this article is all about learning how to use focus stacking in macro photography.
It is often used to reduce noise (for example in astrophotography). Or to remove unwanted distractions, simulate long exposures or produce various special effects.
In macro photography, it produces sharply focused images. The whole depth of the subject from front to back is in focus.
What Is Depth of Field and What Does It Have to Do With Image Stacking
Modern DSLRs don’t shut down the lens aperture until the moment you take the photo. But you don’t see the effect a lower aperture has on depth of field while composing a shot.
To preview the effect, use your camera’s depth-of-field preview button if it has one. More of the scene is in focus at smaller apertures. Particularly if you switch your camera to live view without exposure simulation.
If your camera lacks a depth of field preview button, take a test shot.
The same adjustments will change the depth of field in macro photography as well. But it won’t be by the amount you might expect.
You might have enough depth of field for a normal subject such as a person several metres away. But this will go down as you move the camera closer to the subject.
This presents a particular difficulty in macro photography. Obtaining a large image of a small object on your sensor means getting the camera very close to the subject.