Photograms—cameraless images made by placing small objects over photo-sensitive paper and then exposing them to light—are as old as photography itself. In the ’20s, Man Ray revived them as “Rayographs.” And today, they’re in vogue once again, along with other “antiquarian” techniques such as daguerreotypes, ambrotypes, and tintypes. In his exhibition of photograms at HNTB Architecture, Pradeep Dalal presents images made with objects of varying degrees of translucence, from bits of vegetation to headlight lenses. Dalal’s two-dimensional sculptures succeed only about half the time, but when they do, they’re playful and inspired. At his best, even solid objects—such as his hands—cast unexpectedly complex shadows, thanks to slight movements that blur the outlines. His clear objects are even more intriguing, particularly an assembly of vintage patent-medicine bottles that feature shimmering old-fashioned lettering. Also among the highlights is a work in which Dalal takes those whirligigs that fall off branches, adds some wispy strands of undetermined organic origin and a few flat-topped nails, and creates a fanciful birdlike creature on a perch (pictured). Even images that feature only stand-alone organic material offer sinuously inviting curves, backed by slight tonal ranges of gray. But of Dalal’s photograms, the most striking may be a homage to Minor White’s famous image of a gently flapping, sheer window curtain. Unlike White, Dalal simultaneously manages to capture the reflection of trees and branches—or so it seems. And in this case, it’s not quite clear how he pulled it off. The exhibition is on view from 8:15 a.m. to 5:15 p.m. Monday to Friday, to Monday, Dec. 2, at HNTB Architecture, 421 7th St. NW. Free. (202) 628-7525. (Louis Jacobson)