MANAGE CLOSE FOCUSING DISTANCES
Capture close-up and macro images with ease by working with depth of field and fine focus adjustments
As popular as it may be, macro photography can be considered a highly specialised genre, requiring a specific mindset with regards to lens choice, lighting and focusing. The high magnification and frame-filling compositions, which are common, make any misjudgment in focusing highly visible. At such close focusing distances depth of field is vastly reduced, so the positioning of the focal plane must be tightly controlled if the correct areas of the subject are to be kept sharp. Unfortunately, many of the regularly used focusing techniques fail at macro working distances.
Firstly the minute alterations in focus position required for fine-tuning macro images are too precise for lens distance scales to be of much aid. This thus reduces the viability of zone focusing-like methods, which also fail because we are working with such narrow depth of field.
Furthermore, for the same reason, any change in camera position can have a drastic effect on focus, unlike occasions when a wide lens and smaller aperture setting are in use. Care must be taken not to move the relative position of the sensor to the subject after focus has been confirmed, which removes the focus-recompose approach as a usable option. It is also necessary to compensate for subject motion, due to wind for example, as this too can shift important detail out of the focus zone.
Another complication is the use of autofocus, which in many cases can become a liability in macro photography. Cameras generally exhibit a poorer performance at close focusing distances, leading to lenses ‘hunting’ for focus, thereby slowing the workflow and resulting in missed images. It is advisable to turn off AF, at least at the closest focusing distances, and manually focus while visually inspecting the scene. For maximum success, take many frames to increase the probability of capturing a perfectly focused image, with the subject and lens ideally aligned. Consider using burst mode and altering focus between frames as a means of tipping this probability in your favour.
DP