APERTURE IN PHOTOGRAPHY

Aperture in photography — light and depth of field

Aperture regulates the amount of light passing through the lens and affects depth of field. A smaller f-number means a wider opening, while a larger number means a smaller opening. Its effect should always be assessed together with subject distance, focal length and the background.

Wide aperture: f/1.2–f/2.8

This is a good choice when you want to separate a portrait subject or a detail from the background and are working in low light. Depth of field can be very shallow, so the focus point — usually the eye in a portrait — requires precision. The same f-number produces a different depth of field close up than it does at a greater distance from the subject.

A versatile range: f/4–f/8

A useful range for environmental portraits, street photography, interiors and many product photographs. It gives a greater margin of sharpness while still allowing clear separation between planes.

Landscapes and products: f/8–f/16

In landscape and product photography, f/8–f/11 is often the best starting point for sharpness and depth of field. F/16 is useful when the nearest plane is very close to the lens. F/22 provides even greater depth of field but can reduce microcontrast through diffraction — so use it deliberately, after checking the frame.

Aperture and exposure

Each one-stop reduction in aperture halves the amount of light. To maintain image brightness, you then need to lengthen the exposure, raise ISO or add light. The choice depends on whether freezing motion, image cleanliness or controlling depth of field matters most.

A simple exercise

Set up a stationary subject and take a series at f/2.8, f/5.6, f/8, f/11 and f/16. Keep the framing the same and adjust the shutter speed. Compare the sharpness of the main subject, the appearance of the background and fine details — you will quickly see which range best suits your way of working.