Doctor Who fans will only get half the usual episodes of the cult sci-fi show next year.
The BBC, had been pushing for more than the regular 12 instalments but was told by Capaldi that working harder was not acceptable, both for him and the “exhausted” crew.
“If you did the series all year there’d be casualties - and one would be quality,” said Glasgow-born Capaldi, the twelfth actor to play the Doctor.
“There’s a point where you can’t drive people any harder.”
However the reduced run of Doctor Who episodes will be supplemented by a Christmas special.
But Capaldi has admitted that starring in the role takes its toll on his life.
“Playing the Doctor takes up so much time. It doesn’t leave much room for other things.”
However, fans will be relieved to hear that while Capaldi, a respected as a director and whose credits include winning the 1995 Oscar for Best Short Film for Franz Kafka’s “It’s a Wonderful Life”, has said he will eventually leave the series “that moment hasn’t arrived yet.”
Steven Moffat, the show’s executive producer, has stressed that Capaldi is not quitting his star role.
“Peter is going nowhere,” Mr Moffat said.
Mr Moffat added that the series, which earns the BBC £60 million a year in foreign sales, will continue until at least 2020, despite a fall in ratings this year.
“It is definitely going to last five more years, I’ve seen the business plan. It’s not going anywhere,” he said. “And I think we can go past that. It’s television’s own legend. It will just keep going.”
Capaldi’s co-star Jenna Coleman who plays the Doctor’s assistant announced in September that she was leaving the show to star in a new ITV drama about the life of Queen Victoria.