At first glance, Wolfgang Tillmans's photographs look almost throwaway. His subjects are so varied – friends, foliage, oceans, genitals – that you'd be forgiven for thinking he doesn't give them any thought. But take a step back, and you realise you're looking at one of the most distinct bodies of photographic work of contemporary times. Tillmans asks fundamental questions about how we perceive and deal with the world – and recently, with the pro-Remain posters he created ahead of the EU referendum, the political urgency in his work has come to the fore. This Tate blockbuster is one you won't want to miss.