Moving targets  Sigmar Polke's use of old photos, old engravings
and old porn makes his painting fascinating - and impossible to
pin down. By Adrian Searle Polke: The Fastest Gun in the West,
2002 'A painting is target practice, for painter and viewer
alike.' The Fastest Gun in the West, 2002.  Sigmar Polke is a
man who takes his morning coffee with a big pile of newspapers
and a pair of scissors to hand. He snips things out, headlines
and odd or arresting images, to re-use in his art. For 40 years,
Polke's art has been a very serious joke. Polke, born in Silesia
(now Poland), moved to West Germany in 1953. He later trained -
significantly - as an industrial glass painter, and first became
known, along with Gerhard Richter, as a kind of failed pop
artist. Polke, misunderstood, got his revenge.  Compared to
Polke's, most painting looks feeble, slow-witted, uninventive.
Even though his is an art frequently based on secondary material
- the newspaper clipping, the found photograph, old engravings,
old art, old p