Before there was Mario Testino and Annie Leibovitz, there was Yousuf Karsh. “Karsh 100: A Biography in Images,” on display at the Boston Museum of Fine Arts through Jan. 19, is largely an exploration of Karsh’s strikingly beautiful and expressive black and white portraiture, though it also delves in bits and pieces into both his early work and images outside the portrait milieu. Though these digressions from Karsh’s most famous pieces help elucidate the character of the artist, they cannot compare to the power, intensity, and soulfulness of his signature portraits, which form the bulk of the exhibit.

All four walls of the vast room that houses the collection are lined by photograph upon photograph of Karsh portraits. What is amazing about all of these images is not only the fact that their subjects almost form a Who’s Who of the 20th century, but that each and every one manages to capture some je ne sais quoi of their subject, effortlessly revealing in a single frame either some private moment of the public persona, or some prominent, popular understanding of the individual.

The signature element to the Karsh images is the interplay between black and white, shadow and light, and the crisp, clean, solid lines that lend the prints their clarity and poignant definition.

It is this element that crystallizes the personalities of the subjects in the eyes of the beholder. Eisenhower, Castro, Khrushchev, Kennedy, Bogart, Loren, Karloff, Hepburn, Auden, Hemingway, Shaw, Einstein, Cousteau, Keller, Ernst, Picasso, and O’Keefe all fill the walls with their ineffable essence.

Karsh’s big break came in 1941, with the iconic photo he took of Winston Churchill during one of the former Prime Minister’s visits to Canada. Churchill gazes sternly out of the print. His unrelenting spirit leaps from the image in the lines of his face, in the powerful position of his stance, one hand on his hip, the other on his cane.

The radiant suggestion of a halo playing about his head is a perfect example of Karsh’s use of light: most of his subjects are surrounded by dark backgrounds. Yet this use of light reaches into the luminary aspect of the strong leader who refused to back down to Hitler or endorse a policy of appeasement—not to mention the man for whom the Churchill Martini (six parts gin, hold the vermouth) was named.

From the effortless grace of Audrey Hepburn to the manly vulnerability of Ernest Hemingway to the quiet power of cellist Pablo Casals—bent over his instrument mid-stroke, back to the camera—Karsh teases something elementary out of his subjects, something endlessly representative of their characters and lives, searching for the vulnerable, the revealing, the truth.

Unfortunately, his work in landscapes or scenes of everyday lives does not approach the power of his portraits. While “Calgary, Alberta: Stampede” contains the haze of chaos and dust and the struggle between frightened horse and tense man, images such as this one are the antithesis of the clean and strongly contrasting black and white portraits. “Stampede” and other works from the Canadian Cities Project are unfocused, unclean, and inscrutable.

The exception to this rule comes in a pair of images that Karsh took while on the set of the 1964 film “Zulu,” which show the actual Zulu warriors staring up at movie screens in expressions of pure delight, joy, and wonderment.

Some of Karsh’s earliest work, while not quite so brilliant as those later portraits, prove to be interesting from the historical perspective of the evolution of the artist. Again, these photographs do not have the characteristic crispness yet—a portrait of an unidentified woman has more of the hazy film noir feel—nor do they have the same intense focus on the individual, but they do show Karsh’s beginnings and allow one to see just how far he came.

The text accompanying the collection explains that “Karsh wrote of his fascination with the ‘inward power’ of his sitters. He said that it was his goal to ‘photograph the great in spirit, whether they be famous or humble.’” Truly, if ever there were the ability of a camera to capture the soul, Karsh was able to utilize that power, and this exhibit does a brilliant job of displaying his wonderful talent.