The use of long lenses for distance shots and a flash for close-ups both have flattening effects on the resulting images.
Mitt Romney came out fighting, flattening Newt Gingrich on investments and immigration.
late 14c., "to prostrate oneself," also "to fall flat," from flat (adj.) + -en (1). Meaning "to make flat" is 1620s. Related: Flattened; flattening.