Ah, summer camp. You like moonlight sing-alongs? Gathering twigs for the ol' campfire? No problem. At this camp, they'll uproot whole trees for your bonfire. What is, not surprisingly, the world's first summer camp for studs--actually hopeful body-builders both male and female--opens in New Jersey in June, and believe it, that's a survival challenge in itself. For up to $500 a week, you can bench-press with the best: stars of body-building with awesome Atlas-like titles--Messrs Universe and World, and Ms. Olympia. The "Pro Muscle Camp," run by Pro Muscle Management in Santa Monica, is for dedicated pros and health-conscious amateurs alike, and will include seminars with the experts, sports medicine workshops, videotaped training sessions, suntanning afternoons by a lake renamed "Muscle Beach," and a Best Camper award at the end of each weekly session. Among the first sign- ups--a 15-year-old from North Carolina and a 60-year-old from Florida. It's the latest in fantasy camps that feature, to date, sub-deb etiquette and preteen warfare, diet techniques and computer secrets, theatah and speed-reading. Body-builder and Pro Muscle partner David Zelon, who fondly remembered bunk-bed summers at a Camp Tioga, later found California to be a body-building mecca, "so we decided to bring the mecca back east." In other words, if Muhammad Ali couldn't get to the mountain, "we'd take the mountain to him." For people whose biceps and triceps are more accustomed to bicycling and tricycling than pumping iron, there will be the solace of one of the sponsors: Ben-Gay SportsGel. Lions and Tigers and Docents Through the primeval wilderness of Glendale . . . past the jungle thickets of Long Beach . . . the safari is making its way. A zoo-to-you program by the Greater Los Angeles Zoo Assn. (GLAZA) will take the less-than-fleet-of-foot residents of Southland senior citizen centers and retirement homes on a free wildlife tour, with an armchair visit to the Los Angeles Zoo. Naturally, one showstopper in the 45-minute slide show and discussion is the zoo's huge Galapagos tortoise, which can live up to 180 years. "Wouldn't you love to know what kind of vitamins he takes?" queries the tour guide, to inevitable oohs and aahs. Another crowd-pleaser is the rare Ukari ape, since everyone has a relative just like him--he's completely bald and permanently red-faced. There are a lot of baby animals in the show, too, and the stupefying news that an elephant stays pregnant for 22 months before delivery. Says a GLAZA representative: "People just love that." Picture This Beauty is truth, and vice versa, as modern bureaucrats might have reworded Keats. By those standards, the most truthful object we've seen in a long time is the winning entry in this year's photomicrography contest sponsored by Nikon. Jonathan D. Eisenback, an assistant professor of plant pathology at Virginia Poly- technic Institute and State University (the length of his title is in inverse proportion to the size of his photo-models), won for his character portrait of a roundworm magnified 160 times. He also got an honorable mention for a candid photo of the slime mold Myxomycete capilitium . Among the locals honored for giving us the big picture were John I. Koivula of Santa Monica, who took ninth place for his New Wave aqua-and-orange photo of decomposing copper. And 14th place went to Charles V. Davis of Caltech, for his magnification of a "metal oxide field effect transistor" on a computer screen. All are available in a calendar through Nikon in Garden City, N. Y.; wait until you get a look at the spiral nematodes on Mr. April.