Time Zones is the first major exhibition at Tate Modern devoted exclusively to film and video.
Wolfgang Staehle: Comburg, 2001 (courtesy Postmasters Gallery, New York)
It is a good idea to read the guide first for the rooms are so dark that it is only the feel of thick carpet which indicates that you are entering a new zone.
An 8 minute sequence shows one artist, Bojan Sarcevic, walking through the alleys of Bangkok. You can even see the cameras sometimes. Here are streets the tourists rarely see. But suddenly a passage looks familiar. You are tempted to watch it again to check if he has been walking in a circle.
Fiona Tan: San Sebastian, 2001 (courtesy the artist, and Frith Street Gallery, London)
Wolfgang Staehle provides a live feed, really five second grabs, of a monastic building in Germany. Staehle's last webcam captured the unfolding September 11 events. Here his German webcam has already relayed, to another audience, the rising and falling of scaffolding on the monastery towers. During this exhibition we should see the trees change colour and maybe snow fall.
So it is a pity that Times Zones is not free. This is just the kind of show where you want to be able to drop in as so many people did during the Weather Project. But £6 is too much for a brief return visit to check on the German weather.
• Time Zones continues at Tate Modern until Sunday 2 January; admission £6 (conc £5).