Sling the camera over your shoulder and the world identifies you as tourist, usually excusing most of your photographic indiscretions. A startled passerby in native dress may even manage a smile when you suddenly thrust a lens into his face hoping to add picturesque color to your slide show back home.

But two recent travel advisories issued by the State Department warn that vacationers can find themselves in serious trouble in some countries if they snap photos as indiscriminately as they might in an American national park. Several of the world's governments -- especially those of Eastern Europe but also in Africa and elsewhere -- forbid taking pictures they believe might compromise their national security.

Military installations are an obvious no-no, but you could lose your film, your camera or, indeed, several hours of your freedom by photographing such innocent-seeming subjects as a school building or bridge.

In the African nation of Tanzania, warns the State Department, "People have been detained and/or had their cameras and film confiscated for taking pictures of hospitals, schools, industrial sites, airports, harbors, railway stations, bridges, government buildings."

While travel in Tanzania is "generally safe," says the State Department, the U.S. Embassy in Dar es Salaam recommends against taking photos in built-up areas because many of the restricted buildings or facilities are not clearly marked as out of bounds.

Save your film for Tanzania's game parks where there are no restrictions, suggests the State Department.

A similar travel advisory was issued for another African nation, Zimbabwe. The State Department cautions that "Zimbabwe authorities are extremely sensitive about the photographing of certain installations and buildings, such as government offices, official residences and embassies." It urges visitors to "ask police for permission to photograph before attempting to take pictures of buildings or installations."

At the same time, the State Department warns U.S. visitors to avoid certain areas of Zimbabwe because of "uncertain security conditions." Travelers should expect to be stopped at police and military roadblocks throughout the country, it says.

The State Department's Bureau of Consular Affairs provides no total for the number of photography-related incidents involving Americans in Tanzania and Zimbabwe. However, spokeswoman Ruth Van Heuven says warnings about problems abroad are issued only when "there are enough events of record. We don't put it in a travel advisory lightly."

Americans are so accustomed to snapping almost anything that catches their eye here in the United States that they sometimes forget that in other countries a camera can be an intrusion. While touchy governments may take you for a spy, private citizens often are offended because you are intruding on their privacy. Some peoples fear the camera for religious reasons, believing that a photograph drains away their spirit.

Standard advice to travelers to the Soviet Union and other Eastern European countries is to avoid photographing military and police installations and, for that matter, anyone in a uniform. He or she may consider you suspicious and decide to question you. Other restricted subjects are industrial structures and almost anything connected with transportation -- harbors, bridges, railway stations, airport facilities.

Some travelers enjoy getting a photo of their first step into a new country. But Jonathan Chase, manager of Travel Advisors, a Washington travel agency specializing in East Europe, cautions his clients against taking any photographic memoirs of railway border crossings into communist countries. Keep your camera inside the train window, he says.

Throughout East Europe a common street sign posted on official buildings is the image of a camera with a red slash through it. This means no photos are permitted. If you're not sure whether a site is restricted, ask an official or pay heed to the slogan Chase offers his clients: "If in doubt, leave it out."

The State Department's Van Heuven notes that photographers and their cameras are going to come under close scrutiny in any country that is experiencing protests or other civil unrest and where security concerns are high. The government may, as has South Africa, put a ban on any photos of street disturbances or other signs of civil strife. If you are spotted using your camera, your film is apt to be confiscated, and you may face other penalties.

Travelers who want to know if any travel advisories have been issued for a country they are planning to visit can call the State Department's Citizens Emergency Center in Washington at 647-5225. For details about specific photographic restrictions, travelers should consult the U.S. Embassy in the country concerned.

Professional photographers Julian Calder and John Garrett, authors of "The Traveler's Photography Handbook" (Fielding, 239 pages, $14.95), point out another potential problem. "In most Western countries," they write, "there is no restriction on photography in public places -- but be careful about what is public and what is private property. Invasion of privacy laws apply to photographs of people on their own property ... " Their advice: "Always ask first."

As experienced travelers know, taking photographs may be prohibited inside art museums and religious centers in many parts of the world, including the United States. Often you can expect to be asked to check your camera while you are on a tour.

Insensitive photographers, while not breaking any law, can sometimes offend the citizens of the country by taking uninvited snapshots of them. A first-time traveler abroad should not think of a foreign country as a Disney World where the inhabitants dress in unusual costumes for the delight of tourists. As the spokesman for one foreign tourist office in New York says, her generally welcoming countrymen "don't like to be treated like monkeys in a zoo."

Nor should travelers be quick to capture local townsfolk in unflattering situations, no matter how interesting or comic a slide it will make. Consider your anger if exploring tourists caught you on film as you stepped out the door to pick up the newspaper the first thing in the morning.

Customs can vary within a single nation, so a photographer in a strange city or town -- particularly in the nonwestern world -- should find out what polite practices are regarding the photographing of places and individuals. You may want to consult a tourist information office, local guidebooks or even the clerk at your hotel.

In Australia, for example, some aborigines, especially in the remote countryside, are "definitely sensitive to cameras," says Karen Clifford of the Australian Tourist Commission. They believe "the camera takes away their spirit." Others may permit photos if you ask permission first. The commission urges visitors, for the sake of courtesy, to refrain from sneaking photographs.

Generally, people are pleased to have their picture taken if you ask permission first, but they may be uncooperative if you don't. A Washington visitor to the friendly Caribbean island of Antigua learned this lesson last summer.

Raising his camera to photograph a street scene, he saw several shoppers through his lens suddenly raising their arms and crossing them in front of their faces. Deeply embarrassed, he lowered his camera and put it away for the remainder of the trip.

Do Antiguans object to being photographed?

"I'm sure if you asked, they would agree to let you take their picture," says Victor Carmichael of the Antigua Tourist Board in New York.

Carmichael suggests the city-dwelling Antiguans -- who may often be the target of snapping cameras -- were offering "a sort of friendly negative." The photographer probably had surprised them, and rather than make a fuss they had simply hidden their faces.

A spokeswoman for the Caribbean Tourism Association in New York, which represents 26 Caribbean nations, says she is not aware of any Caribbean country where cameras are unwelcome. "If you shoot a picture just like that they might object," she says. "But if you say, 'Can I take a picture of you?' they're quite happy to let you."

Depending on their economic status, some people may ask for a "token fee," she says. "Or if you're using a Polaroid, they would want one or two copies for themselves."

Sensitivity to cameras is not just a foreign trait. There are places in the United States where photographers must also practice discretion. For example, the Hopi Indians of Arizona have prohibited picture taking in their 13 villages on the Hopi reservation, according to Fred Kootswatewa, a staff member in the office of the vice chairman of the Tribal Council.

The Hopis instituted the ban, he says, "to protect their right of privacy." At the entrance to most villages there is a sign posted beside the roadway warning against taking pictures. Tourist who violate the restriction may be requested to turn over the offending film to tribe members.

JORDAN AND SYRIA: For a traveler interested in ancient history, Jordan and Syria offer a rich array of Greek, Roman and Arab treasures. Shirley Duncan, a Washington-based tour organizer, has put together an 18-day package for the fall that explores the fascinating past of these two Middle Eastern nations.

Participants spend the first week in Jordan, visiting such attractions as the once lost city of Petra and Ma'daba for its fine Byzantine church mosaics. From Amman, the Jordanian capital, the group travels by bus to the ancient Syrian capital of Damascus. Among the sights during the nine-day stay in Syria are Aleppo for its 8th-century mosque and the colorful bazaars; Palmyra, the oasis city of the historic Silk Route; and the magnificent 13th-century Crusaders' castle, Crac des Chevaliers, at Homs.

Accommodations are described as first class. Participants fly Lufthansa from New York via Frankfurt to Amman. Departure is Oct. 8, returning Oct. 25. The cost is $2,750 per person (double occupancy), which includes round-trip air fare from New York and all lodging and meals.

For information: Shirley Duncan, High Adventure Tours, 686-0023, or EWA Travel, 1117 N. 19th St., Suite 1007, Arlington, Va. 22209, (703) 522-2626.

VERMONT FOLIAGE: Vermont Life magazine has published a handy guide to the state's fall foliage. A slender pocket-size volume, "Guide to Fall Foliage," it suggests five drives to see Vermont's colors at their best. It also provides drawings to help foliage fans identify 15 of the most frequently seen tree species. The trees are listed by the fall color of their leaves: yellows, oranges and reds.

The book's Vermont Piedmont Tour suggests a 130-mile loop along back roads wandering the eastern foothills of the Green Mountains. The route ascends into the high country near Mount Killington, a major winter ski resort, and passes close to Plymouth, a photogenic village of white frame homes that is famous as the birthplace of Calvin Coolidge.

To obtain a copy: The books are sold in many bookstores for $3.95. For an additional $2 for postage and handling, a copy can be ordered from Vermont Life, 61 Elm St., Montpelier, Vt. 05602, (802) 828-3241.