Only a few of the Yousuf Karsh photographs on display at the National Portrait Gallery show their subjects out of doors or in natural lighting. Franklin Roosevelt is seen standing beneath a moody sky with three other men in a 1936 shot taken in Canada, and Georgia O’Keeffe sits next to a sliver of light coming from an open window in a 1956 image made in New Mexico. But almost everyone else is indoors, and often in rich and luxurious settings, with the background dark, deep and lustrous, as if painted in oil.

The first of two exhibitions of Karsh’s work at the gallery documents a gift of 109 prints given to the museum by the Armenian-born photographer’s widow, Estrellita Karsh. (Another selection of 27 images will be installed May 2.) The show includes Karsh’s 1941 portrait of Winston Churchill, made immediately after the British prime minister delivered a speech to the Canadian parliament. It is a legendary photograph, as famous for its pure visual power as its historic impact. Churchill is seen in a classic bulldog pose: one hand on his hip, the other holding on to a chair, with a wood-paneled wall behind him.

Karsh had only a few minutes to compose the image, and Churchill wasn’t thrilled to give even that time to the then relatively little-known photographer. The prime minister was also smoking a cigar, which Karsh believed would have marred the final image. As recounted by Karsh, the photographer plucked the cigar from Churchill’s mouth and made his photograph, capturing a scowling, deeply irritated man. That pique read as defiance, and the image (which appeared on the cover of Life magazine and will be seen on a new British five-pound note in 2016) helped define Churchill’s reputation as a pugnacious and heroic last bulwark against Hitler.

It was also an uncharacteristic bit of confrontation on Karsh’s part. Among the famous and fashionable portrait photographers of the past century, Karsh was renowned for being a sympathetic artist, a master of getting the best out of his subjects.

“Karsh is never going to try to get you at an awkward moment,” says Ann Shumard, senior curator of photographs at the NPG. “He’s not a gritty photographer.”

Compare that with an anecdote about Richard Avedon, in an essay by David Travis that introduces the book “Yousuf Karsh: Regarding Heroes.” Both Karsh and Avedon photographed the duke and duchess of Windsor (formerly King Edward VIII of England and Wallis Simpson), with strikingly different results. Karsh’s image shows two distinguished and immaculately dressed people, looking into each other’s eyes with affection. Avedon shows the same couple, staring directly into the camera, seemingly stricken, with the duchess’s face a mask of grotesque theatrical anguish. Avedon claims to have told the bluebloods a made-up a story about a dog run over by a car, causing the animal lovers to assume horrified expressions just as he clicked his camera. It was a trick, to elicit something beyond the carefully rehearsed public face of the two royals.

“This is the portrait that succeeded like no other in illustrating Avedon’s personal opinion that they loved dogs more than they loved Jews,” Travis writes.

Perhaps the Windsors deserved it. They did nothing to deserve their wealth and were guilty of odious alliances and contemptible politics. But tricking a subject into self-revelation wasn’t the kind of thing that Karsh would do. Nor can one be sure that manipulating a photographic subject into spontaneous emotion gets at any real or deeply held truth. We are our masks as much as we are our uncensored selves.

And yet, in his best images, Karsh succeeded in getting beyond the public mask at least as well or maybe better than Avedon. Karsh’s subjects are never startled or discomfited, but they often manifest a private sense of pleasure in themselves that seems unrehearsed.

A 1945 portrait of Frank Lloyd Wright shows the famously strong-willed and self-confident architect smoking a cigarette and bristling with impish, intellectual energy. There is a demonic spirit to the portrait, similar to that captured in a famous picture of the composer Richard Strauss by photographer Edward Steichen. Karsh’s portraits owe something to Steichen’s work, Shumard says, and you can easily see some of the connections, especially the theatricality and the chiaroscuro drama of lighting.

It was old-fashioned work, and that’s probably what made it so attractive to the rich, powerful and famous. Not only were they assured of a sympathetic portrait, but the resulting image was strongly connected to the historical tradition of portraiture. In 1956, Karsh photographed Edward R. Murrow smoking a cigarette, with the rounded corner of a television screen seen over his right shoulder. The reference to Murrow’s trade — television reporting — is decorative yet formal, like the image of a ship in a painted portrait of an admiral or rolling farmland in the background of an image of English gentry. The gelatin silver prints of Karsh’s black-and-white work, full of dramatic contrasts and glistening highlights, also connect the prints with a more painterly version of portraiture. The light shining off Eleanor Roosevelt’s fingernails in a 1944 photograph reminds one of the brilliant white highlights in a still life, highlights that make grapes seem moist and glass reflective.

Karsh witnessed the horrors of the Armenian genocide before fleeing his homeland, ultimately making his way to Canada, where he lived most of his life. It’s possible that early feelings of powerlessness drew him to people with power. He served the elite and made them look good. One of the weakest of the images on display is a color photograph he made in 1991 of Cesar Chavez. Karsh’s color work isn’t nearly as interesting as his black-and-white photography, but in this case, something else is going on.

Chavez, the union and civil rights leader, is seen in a blue sweater vest, standing in a door. The framing makes him seem small, and the dark space behind him has none of the intrigue and luxury found in other Karsh portraits. Chavez doesn’t look particularly well, or hearty, or even engaged. He had achieved more in his life than the duke or duchess of Windsor ever would, but Karsh fails to find the same humanity in Chavez as he does in his more glittery subjects. Karsh didn’t just serve power and celebrity, he served one very particular, establishment definition of it.

Yousuf Karsh: American Portraits

is on view through April 27 at the National Portrait Gallery, Eighth and F streets NW.