Happenstance arranged for Robert Mann Gallery to have its “Small Wonders” exhibition up at the same time Laumont Editions Gallery has “The Big Picture.” The coincidence makes it possible to see photographs as small as 1 inch by 1 1 /2 inches and as big as 72 inches by 91 inches on the same day.The latter is 4,368 times larger than the former.

One advantage the Mann Gallery has with “Small Wonders” is that its walls are able to accommodate more pictures. There are 45, including works by Walker Evans, Minor White, Man Ray, Dorothea Lange, André Kertész — on and on through a roll of greats. Laumont, on the other hand, only has room for nine. Six color works by Joel Sternfeld, Jem Southam, Robert Polidori, and Stephen Shore fill up its main space; three black-and-white pictures by Elliott Erwitt take up a separate alcove. Seeing the two shows in succession is a vivid reminder of the range of photographic possibilities.

The smallest of the works is Ellen Auerbach’s “Jaffa” (1935). Auerbach was the second half of Ringl + Pit, a team of innovative German advertising photographers whose work was influenced by the Bauhaus ideas of the 1920s and ’30s. She and her associate, Grete Stern, fled Germany when Hitler came to power, and Auerbach spent several years in mandate Palestine before coming to America.

This contact print of a 35 mm negative was too small for me to really see. This was partly my fault; I was wearing the eyeglasses I ordinarily wear to exhibitions and I would have been better off with my reading glasses. But even then, properly scanning a 35 mm frame would have been difficult: I always use a magnifying loupe for that purpose. On the gallery’s Web site, the image is 3 inches by 4 1/2 inches, and it is a charming picture of three young boys, maybe Arabs, maybe North African Jews.The print on the wall is a valuable artifact from an important photographic career, but does not afford pleasurable viewing.

Pictures with dimensions above 3 inches, however, are legible and fully expressive.Edward Weston’s “Tina Modotti, Mexico” (1925), a 3 3/4-inchby-2 1/2-inch platinum print, is effective because of its simplicity, delicate tonal values, and sensuousness.Modotti was Weston’s lover, a fellow photographer, a radical leftist, and, according to the Kremlin files, a collaborator in political murder. Weston photographed her from a bit below; her tightly pulled back hair emphasizes her round face. The furrows across her brow; her dark, raised eyebrows; her hooded eyes; and her slightly opened, full mouth give this beautiful woman an introspective cast. But what’s on her mind?

Berenice Abbott’s “James Joyce” (1928) is a touch bigger (3 3/4 inches by 3 inches) and shows the nonchalant author from his knees up.We can see such important details as his rakish fedora, round-rimmed eyeglasses, moustache, and the two rings on his left hand. Most important, the slouch of his body and his fixed gaze give essential clues about his being. Ms. Abbott’s straightforward and efficient style needs no more room than she has here to make itself apparent.

Other treats appear as you work your way along the walls. Because of their small size, the pictures don’t announce themselves until you come upon them, and then they suck you in.The show features one goody after another: James Van Der Zee’s perky young girl with long black ringlets holding an unexplained sign that reads “Positively No Trust” (c. 1920), David Vestal’s plastic “Brooklyn Santa” (1969) looking out from a fire escape above a pizzeria, Paul Strand’s atmospheric “Ile de France, Paris Environs, France” (1951). The exhibition put me in mind of George Herbert’s line, “A box where sweets compacted lie.”

Whereas at Mann the pictures invite your attention, at Laumont they insist on it: Every picture in the gallery can be seen from across the room. Some of the pictures at Mann date back to 1900, and all use techniques available almost from photography’s beginning; those at Laumont are light-jet chromogenic prints freshly made with state-of-the-art equipment. Philippe Laumont toured me through his studio facilities, and the technical ingenuity of these machines is incredible. Did I hear correctly that one of them could deposit a million tiny drops of ink per second, each drop precisely controlled for? They make large, high-quality color prints possible.

Several of these pictures are illusionistic, as much like stage sets as flat-surfaced two-dimensional objects. (The bottoms of the frames are only a few inches above the floor.) It seems possible to step into the forest glade in Jem Southam’s “From the Painter’s Pool Series” (2003); from a distance, the receding ranks of trees give an impression of depth, and close up the detail of individual leaves creates a sense of verisimilitude.

Mr. Southam’s “Burton Bradstock, River Bride” (2000) puts us at the point in Dorset on the southern coast of England where the river discharges into the sea. Here the cliffs provide the sense of depth, and the pebbles the verisimilitude. The color rendition in both pictures is quite plausible.

Stephen Shore’s “Presidio, Texas” (1975) leads us down a yellow dirt road framed by electrical poles and their wires. The long shadows make clear that it is late in the day. There is a mesa in the distance, some simple buildings on the right, a pick-up truck, a black dog with his wagging tail blurred, and most startlingly a man close by wearing a cowboy hat. He is startling because in a 6-foot-by-7 1/2-foot picture, he seems almost life-size.

Robert Polidori’s picture of “Amman, Jordan” (1996) is a massive jigsaw puzzle of gray and tan concrete buildings seen from a distance. Chockablock, they fill the frame side-to-side, top-to-bottom.Nothing is attractive in this cityscape: An invisible but implied humanity lurks within, heaped upon itself. Here, the large format enhances the myriad details that are the point of the image.

“The Big Picture” until August 31 (333 W. 52nd Street, between Eighth and Ninth Avenues, 212-664-0594). “Small Wonders” until August 25 (210 Eleventh Avenue, between 24th and 25th Streets, 212-989-7600).