Heath Ledger’s portrayal of The Joker in Chris Nolan’s latest Batman epic, continues to be the talking point of the movie.

Ledger, who died in January aged just 28, is being praised for what is being described as the most convincing performance of his short career.

Critics, cast and crew were treated to a preview screening on Saturday, and emerged from the theatre applauding the movie wholeheartedly.

"Inevitably there'll be this sense of, 'What could he have achieved if he'd lived?'" said Nolan. “And that's the heartbreaking thing about it, to see somebody achieve such greatness and have all that potential tragically cut short."

The movie hits the big screen on July 17.