A RAY FROM THE SUN KING at the Corcoran has fallen on the National Gallery, where they've brought into the light a companion show of 49 works by Robert Nanteuil.

During his 20 years as portrait engraver to Louis XIV, Nanteuil depicted the powerful: Cardinal Mazarin and finance minister Jean- Baptiste Colbert, as well as members of the royal family, court physicians and high ecclesiastics. His portraits were very popular among collectors, as well as students who published them on their doctoral theses to curry favor with the person whose portrait they used.

Such are the foibles of fashion that now, when we look at the portrait engravings, they remind us of faces on dollar bills -- which is, in fact, this art form's most unremarkable fate.

"Nowadays we favor more spontaneous portraiture -- etchings by Rembrandt," says Diane Russell, the show's curator. "These are obviously extremely finished."

Polished -- Nanteuil mastered every dot and line of the process he made his own -- but revealing nonetheless. They are photographically precise. The seven portraits of the Sun King here show more of the man than the regal state paintings on display now at the Corcoran.

Nanteuil drew the king from life at least four times, making 11 different engravings of him in all. Through his life, he made more than 230 engravings, most of them portraits (and most of them owned by the National Gallery).

Unlike his contemporaries, Nanteuil insisted on drawing from life rather than from paintings by others. So his engravings vividly show the quirks of personality that can only be seen in the flesh.

Most of the subjects share flowing curls and lacy cravats. Nanteuil usually framed the portrait in a stone-like oval inscribed with the sitter's name and title. But for the king, there were certain flourishes: Apollo faces, fleurs- de-lis, crowns, scepters, scales of justice, pillows. In a later portrait, Louis is encircled by a laurel wreath topped with the upper jaws of a lion, whose paws dangle in surrender to the greater power.

A few months before he died, Nanteuil, though ill, made a last journey to Versailles. When he returned to Paris, says curator Russell, "He said he had made a wonderful likeness of the king but it killed him, and he died shortly thereafter." ROBERT NANTEUIL -- At the National Gallery of Art through April 28.