Which aperture?

DO WE USE THE SWEET SPOT, OR STOP DOWN?

The images that we take for the focus stack – and the incremental changes in focus between each – will dictate how much depth of field (DOF) we have, so to an extent we’re free to choose any aperture. Different apertures not only affect DOF, but also sharpness. Narrower apertures can result in diffraction (which softens images), while the ‘sweet spot’ for lens sharpness is usually around f/5.6. But at f/5.6 we found it tricky to record enough sharpness in the segments, resulting in bands of sharpness and blur. This is partly down to the focus rail – a rail that allows for shorter shifts would make things easier, but these can be expensive. As a compromise, we used f/14, which gave enough depth of field in each frame to build a usable and sharper stack.