The art of ISO

ISO is one of digital imaging’s superpowers, giving you the freedom to shoot any time, anywhere and almost in any light. Will Cheung shows how you can harness its potential to improve your photography

The fundamental skill of digital photography is controlling the trinity of camera settings: aperture, shutter speed and ISO. While ISO is a relatively recent recruit to the three, its power is immense and not to be underestimated. Learn the skills to master the three settings and you have rock-solid foundations to build on.

While there have been major innovations with apertures and shutter speeds, on a digital camera they perform essentially the same function as they did on cameras of old. The aperture is the adjustable hole that controls how much light reaches the sensor and the shutter speed is a period of time the sensor is open to receive that light. Yes, apertures can now be set in third and half f/stop increments and there are even lenses with stepless values. Meanwhile the big step forward with shutters is the arrival of the electronic shutter that is silent and has enabled superfast speeds. Fujifilm has had 1/32,000sec for years and it recently upped that to a remarkable 1/180,000sec with its X-H2 and X-T5.

However, while these advancements in apertures and shutter speeds are thoroughly worthwhile, they pale into insignificance when you consider what has happened with ISO in the digital age.

If you need a superfast film, there’s Il ford Delta 3200 and Kodak T-Max 3200, both mono films. For colour, then ISO 800 is the highest speed currently available; there used to be a Konica 3200 print film and you might find the odd roll online.

Look where we are with digital ISO. The native ISO range of almost all digital cameras go beyond ISO 3200, so users can tackle the most challenging lighting.