documentary-style
adj. Relating to photographs, especially those of a wedding, in which the subjects are captured in candid, non-posed scenes.
Other Forms
Examples
2002
The Cheneys and the Mihaloviches hired Black Dog Imageworks of Kansas City to photograph their weddings. Black Dog shoots black and white overwhelmingly, and plenty of people call the company for just that reason.

"I know there's a resurgence in interest in black and white — weddings especially," said Rachel Meiring, one of the company's two wedding photographers.

The move to black and white hasn't occurred in isolation. It generally goes along with a grainy texture, wide-angle lenses and a spontaneous, documentary-style approach.
—Karen Uhlenhuth, “Back in black; More people are opting for the timeless and classy look in photographs,” Kansas City Star, June 18, 2002
1997 (earliest)
Besides shooting in black and white, some photographers are also opting for more candid, journalistic-style shots. . . . "Who will be shooting the wedding, and what is his or her background in photography? " If you want more documentary-style shots, you may want a photographer with a photojournalism background.
—Eva-Marie Ayala, “Something old, something new, something borrowed, something black and white,” Fort Worth Star Telegram, July 30, 1997
Notes
The New York Times reported last weekend that this kind of photography — they called it documentary wedding photography — is becoming popular at weddings as modern brides and grooms eschew the traditional firing squad photo (also known as a Castro photo) where the photographer lines up the subjects and shoots them. This naturalistic photography has also been described as journalistic-style, an adjective that makes a convenient appearance in the earliest citation for documentary-style.