HE was known, simply and memorably, by one name: Nadar. If he had not existed, 19th-century Paris would have had to invent him, for he epitomized the urbane vigor and creative restlessness of that exceptional time and place.
He was friend and colleague to most of the leading artists, writers, and intellectuals of his day -- bohemian and mainstream. He stirred the public first as a left-wing caricaturist and partisan art critic, and later as a champion of flying machines and manned aviation. He built the largest hot-air balloon of his day, flew reconnaisance missions in the Franco-Prussian War, and was the basis for the hero in Jules Verne's ''From the Earth to the Moon.''
Yet this excessively extroverted man is remembered for what is, at its heart, an intimate and highly personal art form: photographic portraiture. In the brief span of a decade, beginning in 1854, Nadar brought to the still-young invention of photography an eloquence and psychological depth few thought possible, and set a standard for portraiture that has rarely been met since.
Photographs rarely shown
Nearly 100 of Nadar's remarkable photographs are on display at the Metropolitan Museum of Art in the first extensive survey of the artist's work seen in this country. Organized in collaboration with the Musee d'Orsay in Paris, the exhibit features numerous images seldom or never before seen outside France.
In some cases, for the first time in a century modern audiences may view Nadar as his contemporaries viewed him, with all the subtlety and rich tonal nuance of the purplish-brown prints he made, and appreciate the mastery with which he transformed a rather basic photographic technique into enduring art. Yet what is most striking is the immediacy and rapport the pictures project.
Nadar was born Felix Tournachon, the son of an unsuccessful but high-minded publisher of, among others, the elder Alexander Dumas's writings. Felix, who chose a pseudonym when only a schoolboy, studied medicine briefly before beginning a career drawing caricatures for the liberal Paris press. It was not until he was almost 35 that Nadar first explored photography, working initially with his younger brother, Adrien.
These early collaborations, which form the first part of the Met exhibit, demonstrate Nadar's ability to coax meaning and resonance into a photograph. In a series of portraits attributed to both men, it is clear which pictures were orchestrated by the sensual but uninspired Adrien, and which by his more talented brother.
Portraits of a clown
The crowning achievement of this period is a portrait suite of the clown Pierrot, the creation of celebrated mime Charles Deburau. The 14-picture sequence explores a wide range of gestures and expressions, each marked by a suppleness of movement and light. Evidence suggests that Felix was the dominant influence on the series, but it was Adrien, calling himself ''Nadar jeune,'' or Nadar the younger, who entered the pictures in a competition and won a gold medal.
In 1856, Nadar sued Adrien for the rights to his name and established his own photographic studio. In the ensuing three years, a Who's Who of French artistic and intellectual giants, including Daumier, Berlioz, Millet, Delacroix, and even his father's old client Dumas, sat before his camera. As this body of work unfolds in the exhibit, we see Nadar rise to the heights of his own genius.
As a caricaturist, Nadar lacked an ability to go for the jugular. It is precisely this compassion that supports his photography. He practiced portraiture as a collaboration between sitter and photographer, requiring a balance of opposites: detachment and empathy, scrutiny and reserve, bluntness and praise.
He reveals the composer Rossini, looking faintly like Tony Bennett, as both affable and unapproachable. Baudelaire, a close friend, is intense and elusive. Even his self-portrait depicts a man both passionate and calculating.
The pictures of this, Nadar's highest period, are profoundly candid, yet many of them also reflect what the exhibition catalog calls his ''capacity for admiration.'' Affinity and mutual respect suffuse the portraits, and it's this warmth that sets Nadar apart.
Other techniques tried
By 1860, however, photography held few remaining challenges for Nadar, though he briefly ventured down other avenues. He pioneered the use of artificial light, using it to photograph Paris's catacombs and sewers. He applied his interest in aeronautics to a study of early helicopters, and in medicine, to a clinical yet compelling series on hermaphrodites. One of his most unusual pictures is a mysterious, oddly beautiful image of a banker's outstretched hand.
Yet portraiture occupied the man only rarely, as in 1864, when he created a stunning series of the young Sarah Bernhardt. While the studio bearing his name persisted into the 1940s, Nadar himself drifted to other interests, particularly the construction and flight of a behemoth hot-air balloon, the Geant. Like a pilot riding his giant airship into the clouds, Nadar was by then the acknowledged master of the photo-portrait, a height from which he has yet to come down.