MY COLLEAGUE Steve Barr is about as big a baseball fan as they come. So he was overjoyed earlier this year when I told him Brooklyn Dodger great Jackie Robinson was going to be honored on a postage stamp.

But when he saw the Robinson stamp, part of this year's huge Celebrate the Century stamp series, Barr was crestfallen. Robinson got only one stamp on a sheet of 15 and, frankly, Barr didn't want the other stamps.

Steve just wanted some Robinson stamps to put on letters. It was, he said the other day, just "too darned expensive" to buy 15 stamps when you only want one of them.

Barr is not a stamp collector, but he is a typical postal customer. His reasoning about stamp purchases is one of the reasons why I fear the Celebrate the Century stamps have not been as widely used as officials expected when they planned the blockbuster series and agreed to spend $100 million promoting them. For a stamp to have an impact in America, people should be able to buy them by the sheet, use the stamps on their letters and then move on to a new stamp.

With 150 stamps planned for 10 separate sheets in the Celebrate the Century series, these seem to be the stamps that rarely get used on letters. Sure, that will make the Postal Service a lot richer, but the odds are extremely slim that you'll ever see one of the stamps you like on an envelope. You could call these stamps the invisible stamp series.

And, as of last week, there were 15 more stamps, all celebrating the 1950s. These are stamps that I would have thought the public would be clamoring for. That zany redhead, Lucille Ball, is on one, so is Dr. Seuss's rhyming cat in a hat and World Series rivals the New York Yankees and Brooklyn Dodgers.

Others to be honored in the series, selected by the public in national balloting, include: heavyweight boxing champion Rocky Marciano, drive-in movies, rock 'n' roll music, public school desegregation, the Korean War, stock car racing, New York Giant Bobby Thompson's thundering home run in 1951 ("The Shot Heard 'Round the World"), 3-D movies, the polio vaccine, U.S. satellites, teen fashions, and auto tail fins and chrome.

The Postal Service has printed 188 million of the stamps, which means there are about 12.5 million of each stamp being sold. That's extremely low, even for a commemorative stamp. The stamps were printed by Ashton-Potter USA on offset-intaglio presses.

THERE'S a second cancer awareness stamp on sale at your local post office. Unlike the breast cancer stamp that sells for 40 cents and includes a 7-cent surcharge for research, this one is an ordinary commemorative. It sells for 33 cents, but it has a colorful history, linked to that of the breast cancer stamp.

In one of his last acts as postmaster general, Marvin T. Runyon approved the prostate cancer stamp, perhaps in hopes it would ward off Congressional pressure for a second fund-raising semi-postal like the breast cancer stamp. William J. Henderson, who replaced Runyon last year, has said he likes the community involvement that the breast cancer stamp has brought the Postal Service, a hint that more semi-postals may be in the agency's future.

Even as an ordinary commemorative the prostate cancer stamp has produced its share of controversy. In March, two physicians who practice at a veterans hospital in Vermont attacked the stamp in the New England Journal of Medicine for wording that recommends "annual checkups and tests" to fight the disease.

Steven Woloshin and Lisa M. Schwartz argued in the Journal that it is not good medicine to suggest that all men should undergo annual checks, calling that advice "misguided and counterproductive." They recommended the agency stop issuing health stamps, saying the Postal Service had fallen victim to advocacy groups for specific diseases.

Postal officials denied the charge, but the agency has been quick to point out in subsequent news releases that its new stamp "does not endorse any particular testing method," but encourages men "to discuss testing options with their health care provider."

Designed by Michael Cronan of San Francisco, the 33-cent stamp which features an orange circle with an arrow -- a male symbol -- along with the wording "Prostate Cancer Awareness."

Avery Dennison has printed 78 million of the self-adhesive stamps on its gravure presses. The stamps will be sold in sheets of 20.

And, speaking of the breast cancer stamp, as of late April the Postal Service reported it had sold 85 million of the 40-cent stamps, raising $6.6 million for research.

NAPEX '99, a stamp show , will be held at the McLean Hilton Hotel, 7920 Jones Branch Dr., Friday and Saturday from 10 to 6 and Sunday from 10 to 4. Admission is free. Call 703/820-8573.

INDIVIDUALS seeking first-day cancellations of the Celebrate the Century and prostate cancer awareness stamps should purchase the stamps at their local post office and place them on addressed envelopes. These should be mailed in a larger envelope to either: Celebrate the Century Stamps, Postmaster, 1883 Main St., Springfield MA 01101-9991 or Prostate Cancer Awareness Stamps, Postmaster, 8225 Cross Park Dr., Austin, TX 78710-9991. Requests for the Celebrate the Century stamps should be postmarked by June 25 and the prostate cancer awareness stamp by June 27.

Next week in this space: Photography columnist Frank Van Riper.

CAPTION: The prostate cancer awareness stamp is generating controversy.