Conrad Martens (after) ( 1801 - 1878 ) was a British painter. Conrad Martens (after) s works have been put up for auction numerous times, with realized prices surpassing estimated prices, varying from 7800 USD for Sydney Harbour from Darling Point in 2006 to 20523.66 USD for The Valley of The Macdonald, Cumberland, New South Wales, Australia in 2009 , based on the size and medium of the artwork.