Got an eye for a striking photograph? Well, it's time to do battle – this Saturday, there's an all-day photography challenge taking place across London.
Organised by collective Street Photography International, participants will be challenged to capture photos that match five themes, revealed on the day, as they wend their way between waypoints across central London.
At the end of the eight-hour competition period, you'll be able to submit your 15 favourite shots for consideration by the judges – and join your rivals for a few drinks – with winners picking up prizes from Lomography as well as masterclasses from the organisers.
Whether you're wielding a DSLR or an iPhone, you're invited to take part.