We all collect photographs. Some in albums, others in drawers and many -- "who knows where?" These visual records remind us of events, people and places we have known. Looking at them, we can relive the past.

I just had that opportunity, recalling my past experiences as a National Geographic photographer by looking through my "take" of some 12 years of staff shooting between 1960 and 1972.

Looking through some 150,000 chromes -- which took three weeks of daily peering over a light table -- I learned some things; much of it technical, but more a reflection of how great a value pictures are in preserving the past.

Most of us would never shoot that many pictures; in fact, on an average of five 36-exposure rolls of film per year the normal snapper wouldn't make it in a lifetime or more. What I had was a concentrated professional output, the equivalent of most highly active pro photographers.

Among the lessons: CAPTION CARDS: The technique at the Geographic is to write the information down as completely as possible when the pictures are taken; not necessarily a separate caption each time the button is pressed, but a description of the action and the time and place. These cards were invaluable in giving exact information that my lousy memory could never provide. (Actually, the cards I refer to were originally in booklets with a spiral binding. Each page was backed up by a copy made by the pressure of the pen. The original was sent with the film and the copy retained by the field photographer.)

Reading the caption cards reminded me of how poorly I keep track of my personal pictures and what a good idea it would be to take notes at the time and file them with the photos. The cards would be a great memory-jogger -- especially when younger members of the family are convinced that the old man's memory is slipping. COLOR FILMS: The obvious technical fact that came glaringly through is that when chroming for the future, Koda is better than Ekta. Many of the original '60s slides had turned blue on Ektachrome, while the Kodachromes still shone with original color. On roll after roll I wished I'd shot with the slower film. And this color shift was evident despite the excellent storage the Geographic provides: The slides are kept in air-conditioned rooms in their original yellow boxes stacked in cardboard containers that hold about 60 rolls each.

The boxes in which your film is returned offer good light-tight, dust-free storage. These can be packed into larger boxes for conviences, with labels or just notes written on the boxes describing the contents. And if you shoot negative color, it's even simpler -- just file the negatives inside the envelope they come back in, with a notation of the contents. FILING: Another obvious technical fact was that there were many poor exposures that should have been filed in the round 13-inch wastebasket and not exposed to the glaringly objective illumination of the light table. We all miss exposures -- pro as well as amateur; these overs and under just take up space, and unless they're "one of a kind" they should be chucked. (The technique that the pros use is to grossly overshoot to make sure each subject is covered.

A mistake made by many amateurs is to think that by special darkroom magic their mistakes can be turned into masterpieces. Far better to take another shot or two with different exposure settings to make sure. THE BRIGHT SIDE: On the positive side, the information on each chrome was enormous. Under the eye-loupe the events stood out enlarged on the light table. With magnification the action could be examined in detail, the costumes enlarged and the scene re-explored. The color of the foliage and flowers, the trees and landscapes and snow and sand were preserved. Over and over the thought occurred that photography is a wonderful way to keep a reminder of exactly how things looked.

Artist friends tell me of how they use photographs as an aid to painting. In fact, with some, it's more than an aid; it can be a direct copy. (I learned this from a landscape painter who complained to me of the general sameness of his scenes. On discussion, the cause was apparent -- he used only a 50-mm lens. I suggested trying teles and wide-angles for a different perspective.)

Writers, too, use photos as an aid to recall the visual scene. True, they can't recreate the other informational senses of touch, taste and hearing, but the visuals serve as a memory jog for these others as well. I know writers who sue visual information provided by their cameras tgo augment their memory.

But the information contained in pictures is not only for the specialist.

On a personal level, the print or slide can bring back memories to all of us. Pictures are a good way to preserve the past. But to make this information readily available, you should have a system of organizing your slides and snaps. It may not seem all that necessary today -- but they are accumulating daily and you should give some thought to the future collection as you're making the present click. Ther active summer shooting time is good for a start.