Q: I am going on a whale-watch expedition and would appreciate some photographic suggestions.

I own a Minolta XG-7 and a 135-mm lens and a doubler. Usually, I use film with a 100 ASA rating. Can you tell me if I should use faster film, what time of day to try for good shots and any other tips ? A: To answer this questions, I decided to go on a whale-watching expedition and get up-to-date, first-hand information.

I joined a group out of Redondo Beach, California. The 65-foot-long, 25-ton Voyager , I was told, left "promptly at 8:30 a.m." and stragglers "would be left behind."

The schedule was more lenient than that: It took until nearly 10 to board the 140-odd whale-watchers -- including Bemi DeBus, president of the American Cetacean Society, and two other expert whale guides, Libby Helius and Jane Shafer.

Bemi, over the ship's loudspeaker, filled us in on whale lore as the vorager headed out to sea.

We learned that the "apneatic" breathing pattern of the wales is predictable and serves as a guide to whale-watching. Every four minutes the whales come up for a breath of air. On surfacing they expel the air at a velocity of up to 100 miles per hour as they exchange 90 percent of the air in their lungs with each breath. This action causes a water spout that reaches 12 to 14 feet above the water. That's what the lookouts on the whaling ships watched when they called "thar she blows."

Other visible signs of whales are "breeching," when they lunge out of the water, sometimes as much as two-thirds of their length; "flunking," when the tail is exposed as they dive; "spy-hopping," when the whale brings its head above water to look around, and "foot prints," the smooth round ripples left after a dive.

The first sighting happened within the hour of our departure. Two California Gray, or sperm, whales were sighted about 700 feet from the boat. Because only their backs protruded above the water and they were swimming in tandem, the first thought that came to mind was the Loch Ness legend. Cameras and binoculars were immediately trained on this vast huld, which, like the tip on an iceberg, only gave an indication of the enormous mass still underwater. Everyone waited expectantly to see how much more of the leviathan would show; but we were disappointed -- it sank into the sea.

But now the chase was on and our skipper headed the boat in the direction of the "footprints" left on the water -- and the four-minute countdown started on our watches. It was exciting. Where would she blow next?

Our course depended more on luck than navigation. We missed the next sighting but were able to pick up the trial. Throughout the voyage we were rewarded with several "flukings" where the tail was entirely out of water, and water spouts that stood out on the flat sea surface. Unfortunately, there were no "breechings"" -- which are the most spectacular pictorially but happen very seldom.

One veteran whale-watcher said she's seen only one breeching during seven years -- and that was so near the boat that it took he by surprise and she missed the picture. She added that it is not at all unusual for passengers to forget their cameras in the excitement.

But in our party cameras were out all over the boat, and at each sighting there was good-natured jockeying for position.

The equipment varied from Instamatics to extreme telephotos -- and everything in between.

Obviously, the normal and wide-angle lenses couldn't reach out far enough for a sizable image -- unless there was a once-in-a-lifetime breeching alongside the boat. The consensus was that a 200-mm to a 300-mm telephoto was needed for a 35-mm format. There were occasions when a average tele of around 100 mm could take in a good view of a fluke rising with small boats in the background or close-ups of dolphins swimming boatside and sea lions perched on a buoy. Sailing boats and seascapes could be taken with normal focal-length lenses and even the most basic cameras.

The best gear aboard was sported by photographer Miles Patrick, who carried a Nikon equipped with a motor drive and a zoom lens of 50 mm to 300 mm, while the smallest camera with telephoto capabilities was a Pentax 100 with an assortment of lenses.

Based on what I learned on this trip, and previous experience, I wwould suggest the following equipment, film and accessories for successful whale-snapping.

A telephoto lens of at least 200 mm on a 35-mm camera or the same proportionate lens on other sizes. The ideal is a 300-mm -- especially a zoom that permits in-close shots for the unexpected views without the loss in time of changing lenses. Additionally, a motor drive is useful because the whales surface only briefly.

Fast outdoor color film of 400 ASA, which will permit high shutter speeds to counteract the rocking of the boat and allow a tele lens to be stopped down for more depth of field.

Useful accessories are: A polarizing filter to cut surface water reflections, lens cleaner and tissue to wipe the sea spray off the lens and a plastic bag to protect the camera in case of heavy sea or rain.

To find out about cruises and whales in general call or write to American Cetacean Society, 213/548-6279, Box 4416, San Pedro, California 90731.