Bamber Gascoigne has opened the Royal Society of Painter-Printmakers annual exhibition at the Bankside Gallery.
"You are all very faithful to your craft," he told the members before briefly attacking what he called 'ink jet prints'.
"We must try and stop confusion between machine printed images and hand printed images," said Bamber Gascoigne who is author of a controversial book called How to Identify Prints: A Complete Guide to Manual and Mechanical Processes from Woodcut to Inkjet.
However, the former University Challenge presenter added: "We are living again in an age of real interest in prints which is wonderful. One thinks back to the days of printer-etchers like Whistler.
Exhibitors at the Bankside Gallery exhibition include Bermondsey-based Norman Ackroyd RA who is showing an aquatint of the Connemara coast and Angie Lewin of the St Judes Gallery group.
There is a depiction of Southwark's lost Tabard Inn as a timber-framed building in Michael Barratt's Canterbury Tales etching. He also depicts St Thomas A Watering which is now the crossroads outside Tesco in the Old Kent Road.
Janet Brooke's Something New lino cut is a view of The Shard rising above the tower of St Thomas' Church.
A small wood engraving by John Bryce features Tower Bridge in bright light.
Among those receiving a prize at the exhibition launch on Thursday evening was the son of the celebrated Edward Bawden, Richard Bawden, who was awarded the Aberystwyth University School Prize for a picture of the interior of his house.
Bamber Gascoigne was introduced by leading wood engraver and Society president Hilary Paynter.