Few artists can communicate in as bright and firm shorthand as Alex Katz. Inaugurating a new kind of figurative painting in response to the Abstract Expressionism that dominated New York in his early years, the 89-year-old artist has refined a style that even now, in the age of the instant image, looks quicker than a passing moment, despite its careful, painstaking realisation on large-scale canvases. In one of the biggest shows of his work in London, the Serpentine Gallery takes us from the mid-1990s to the present in revealing Katz as an artist who, instead of going through contradictory stages throughout a long career, has perfected one, singular way of seizing, as he calls his subjects, “quick things passing”.

That said, Katz’s work nods to a diverse array of influences, from Abstract Expressionism’s grand dimensions to the vacant flatness of Pop Art and elegant leanness of Minimalism. His is a colloquial tone akin to his friend Frank O’Hara’s, most visible in pictures such as Emma or Vivien, which show his subject in holiday casualwear standing in six different poses, like in a series of snapshots. However, like O’Hara, the everyday for Katz also contains the absolute and ultimately sacred, exemplified by the large-scale portrait of the artist’s wife, Ada – spare and disarming in a simplified 2015 likeness. Since 1959, he has painted her more than 200 times, and yet this portrait has the quality of a first glance, one moving laterally (across the large canvas) as well as inwardly, with a suggestiveness that doesn’t require searching for depths, and yet inevitably finding them.

It is Katz’s talent to move in the shallows of a subject while penetrating it that animates not only his paintings of people, but also his more rarely displayed landscapes. Like a modern Gainsborough, whose landscapes were often similarly ignored in favour of portraits, Katz has the stylistic brevity of an illustrator that can fool the untrained eye into thinking: that’s easy. But a closer look at the brilliant sharp flickers in his woodlands or dark waters in a stream, not to mention the vast, inky paintings made amid trees in New York in 1995, reveal the masterful sleight of hand that has become Katz’s trademark. The Serpentine, surrounded by Hyde Park, makes for the perfect setting 

Alex Katz: Quick Light is at the Serpentine Gallery, London, until 11 September.