Yogi Berra is famous for his astute observations.

Once Yogi said something along the lines of "You can see a lot just by observing." When asked about it, he 'fessed up: Of course, he had said it. He would still say as much again today.

Beyond the unintended humor, there's a certain logic to this Hall of Fame catcher's words. Collectors too can see a lot just by observing. Let's look and see what we can turn up.

Three-dimensional images are a popular collecting field. Ranging from century-old stereo view cards to jet-age printed stereograms, these perspective-blowing images are popular with kids and adults alike.

In the second half of the 19th century and up until the Great Depression, stereo card photographs and viewers were found in many homes. The traditional fare consisted of scenic wonders, historical sites, and humorous tales issued in series.

Hand-held and table-mounted viewers were still popular in many grandparents' homes of the last generation. Today, thousands of varieties of these stereo cards are available to collectors from $1 to more than $100, depending on subject matter and condition.

Such 3-D images are not new to vintage sports collectors, either. Manufacturers of sports collectibles years ago capitalized on the long tradition of 3-D parlor, travel photography. Stereo cards of baseball, football and boxing are known to collectors.

With newer technology, stereo viewers and photos were made more compact, cheaper and more efficiently produced. Several sports subjects emerged during the Great Depression.

Back in the '30s Novelview company produced 3-D film strips of the talented St. Louis pitcher Dizzy Dean and the perennially powerful New York Yankees. Strips of the 1936 World Series between Joe McCarthy's Yanks and Bill Terry's Giants are very much in demand with collectors. All of these strips are quite rare and expensive.

From a slightly later era, another appealing but little known vintage sports 3-D series were Stori-View 3-D slides. A St. Louis firm, Church-Craft Pictures, Inc. marketed these rectangular stereo slides and a patented viewer. The company's forte were children's stories and religious themes.

The Stori-View six-slide sets were marketed for 49 cents and advertised nationally in Life magazine following World War II. One six-card set is of special interest to vintage sports collectors. Stori-View Number 801 is an instructional slide series styled "How to Catch" by All-Star backstop and AL MVP Yogi Berra.

The slides feature two similar but slightly different views of the legendary catcher. Actual transparencies are mounted in a cardboard holder. The scientific principle of parallax makes Yogi look three-dimensional.

Yogi's advice includes giving a sign to the pitcher, presenting the target, catching a wide throw, throwing, covering home plate and catching pop fouls. A typical comment by the Yankee backstop is his advice for covering the plate: "On a tag play at home with the ball coming from third or shortstop, square off facing the thrower. Don't block the plate completely, but show the runner part of it. Upon receiving the throw, drop to your left knee, and put the mitt down in front of the plate."

Stori-Views were never as popular as the more familiar View-Master images when they were issued. Thus, they are rarely encountered today. That largely translates into a seller's market. I obtained a virtually pristine set of the Yogi instructional series a decade ago at the National Sports Collectors Show for $150. Since then, I've seen examples in poor condition cheaper.

Locating viewers for these unique images can be a trick, too. These sometimes appear in toy magazines or on-line auctions. Best bet: try toy shows, where they are available and generally not expensive. Acceptable, working viewers can be obtained for under $20. Sometimes, cheaper viewers are defective. It pays to check when purchasing.

So take Yogi's advice and look for 3-D sports images. After all, "You can see a lot just by observing." You might learn how to block the plate, or who knows just what else you might turn up?

Fred Reed is former News Editor of Coin World and Vice-President of Beckett Publications. A collector for 40 years, Reed is a member of most national coin and stamp organizations. He is also Secretary of Society of Paper Money Collectors. SPMC awarded Reed its lifetime achievement award for his groundbreaking Civil War Encased Stamps: The Issuers and Their Times, one of his five books. Reed has also written on coins and currency, tokens and medals, stamps, comic books, post cards, Beanie Babies, sports cards and collectibles, engravings and lithographs, movie memorabilia, autographs, antique photography, and Civil War artifacts, all of which he avidly collects. He is currently penning two books on the entertainment careers of professional athletes; another on the first family of American sculpture, James Earle Fraser and Laura Gardin Fraser; yet another titled "Abraham Lincoln Pictorial Treasury;" one on the career and collectibles of Yogi Berra, and a murder mystery set during the 1870 baseball season. Reed is a long time member of the American Society of Magazine Editors, the Dallas Press Club and the Society for American Baseball Research.