PHILADELPHIA — When technology dashes forward, taste pussyfoots behind. Photography emerged around 1839, independently, in England and France. Through trial and error, the earliest practitioners learned for themselves how to use and improve the new processes. For aesthetic guidance, however, they relied on what they already knew.

The tension between the promise of the new and the tug of the old is one of the fascinations of “From Today, Painting Is Dead: Early Photography in Britain and France,” an exhibition at the Barnes Foundation in Philadelphia through May 12. The premature obituary in the exhibition title was supposedly pronounced by Paul Delaroche, a successful Parisian artist; and it is usually understood as an expression of painters’ anxiety that the new invention would kill their source of livelihood.

But the opening of opportunity more than compensated for any slammed doors. Some of the photographers in the Barnes exhibition — Gustave Le Gray, Roger Fenton and Charles Nègre — began as painting students of Delaroche and became photographers. Today their reputations outshine their teacher’s.