Focus, focus where are you?

One frame of a 40 image capture to have the appropriate depth of field

Focus stacking is a photographic technique specifically designed to overcome the inherent limitations of a narrow depth of field, which is especially common in macro and close-up photography. In these scenarios, achieving sharp focus across the entire subject can be quite challenging due to the limited plane of focus at very close distances. To create a focus stack, a photographer captures multiple images of the same scene, each taken at slightly different focus distances.

This method ensures that various planes and details of the subject are sharply focused in at least one of the shots. Technical precision plays an essential role in this process: the camera must be securely mounted on a stable tripod to prevent any unwanted movement between frames, and manual focus adjustments are generally preferred to maintain consistency throughout the sequence.

The steps between focus points need to be small and carefully controlled to provide ample overlap; in macro photography, this often means capturing anywhere from 5 to over a 100 images, depending on factors like the subject’s depth and the chosen lens aperture. This adequate overlap is vital because it allows the focus stacking software to seamlessly combine the sharpest portions of each individual photo, resulting in a final composite image with an exceptionally extensive depth of field that retains both technical clarity and intricate detail across the entire frame.

Capturing the shot

A successful focus stacked image relies heavily on a solid and sturdy tripod to ensure complete stability throughout the entire capture process, preventing any unwanted shift or movement in composition between shots.
Though it is worth mentioning there are techniques which are handheld, such as moving your camera through the scene - a skill which takes a lot of time to perfect!

Photographers can either utilise the in-camera focus stacking feature, if their camera supports it, or manually adjust the focus incrementally between frames; alternatively, a precision tool such as a focus rail can provide exceptionally fine control over focal plane increments for more accurate results.

It is crucial to use manual settings for aperture, shutter speed, and ISO in order to maintain consistent exposure across all frames, avoiding any variations that could complicate or degrade the stacking process. Additionally, carefully positioned external lighting can be employed not only to ensure an even, balanced exposure but also to introduce artistic flair, allowing for controlled highlights and shadows that significantly enhance the overall depth and quality of the final composite image.

For a more in-depth guide to technique, i found this blog from Digital Photography School covers the basics: https://digital-photography-school.com/a-beginners-guide-to-focus-stacking/

In my next blog i’ll look at what to do with all these image frames once you have them.

The final output after image stacking