Isn't it nice when things are predictable in photography? The amount of grain that comes from a particular film is one of those constants. With an increase in ASA rating or film sensitivity comes an increase in grain.

For the finest grain and the sharpest image, start with the lowest ASA film available. For the sharpest 35mm black and white, use Panatomic X (ASA 32) AND FOR THE BEST COLOR, SHOOT WITH KODACHROME 25 (ASA 25). Enlargements made from 35mm Kodachrome 25 slides can be four by six feet in size, and still look sharp and not grainy.

But grain isn't the only consideration in choice of film: We also want speed, and for this we use higher granularity films.

The obvious compromise is to choose a film in the middle sensitivity range that gives the best of both grain and speed. So these in-between emulsions are the real workhorses. Their emulsion ratings fall in the ASA 100 range. a

There are occasions when quality isn't paramount. Sometimes it's just the ability to take a shot, any shot, in dim light that counts. For these occasions, the high-speed 400 emulsions are the answer.

The photographic dilemma is that there is no "perfect" all-purpose film. We have to choose the right film for the best possible picture. But even here there are different answers. And these are different answers. And these depend on how far we want or need to go for our own satisfaction.

If we're ordinary snapshooters who want to preserve the moment for a photo album or a slide projected on a home movie screen, then the median ASA 100-rated films are adequate.

On the other hand, if our picture threshold has been raised to the Ansel Adams-type scenic and we are making our own enlargements, then grain becomes a factor and back we go to the lowest ASA ratings.

Then there is the third consideration, that we want to shoot strictly existing-light photo-journalism, or that we not only don't "mind" the grain, but love it when it golfballs up to interesting patterns. Obviously then, we go for the fastest film available.

But whether we go for slow, medium or fast films, there are other ways to control grain than choice of film alone.

One of these ways is exact exposure. Over-exposure will increase grain and the visual lack of sharpness of any film. (This is the reason that professionals conduct their own sensitivity test and often use the film at an approximate half-stop higher ASA, such as Kodachrome 25 at ASA 32.) You have to be very careful on this tightrope exposure, so that you don't fall to underexposure.

Another way that visible film grain is increased is by overdevelopment, or the use of high-energy developers.

Images loss and grain increase can come about through faulty processing. Too much agitation, too little agitation and differences in temperture between the solutions are some of the offenders.

What then is a practical photographic attitude toward grain?

First of all, if you've never heard of grain before and it hasn't bothered you, then just forget it. The competing film manufacturing companies and the reputable labs stay up all night worrying about grain, so let them solve the problem. Why lose sleep over it?

If you're sending all your film to the labs and especially if all you shoot is color (and most of us do), then try the different films recommended for each type of picture-taking. For average snaps both indoors in the sun and indoors with flash, use the popular mid-range ASA films. For those dim-light photos such as indoor candids and night illumination, pick up a roll o ASA 400. And if you're shooting by warm light, such as candlelight, indoor tungsten and theater spotlighting, use Tungsten Type B film. And for best results, use the films at their rated ASA settings; don't push them -- the results aren't that great and you'll just pay more for the service.

If you're into photography as an avid amateur or practicing professional, then you'll have more leeway, and more headaches. Test your film before using by making a series of exposures in half-stop increments from the recommended settings.

That is: if the exposure at say ASA 100, is f11 at 1/25th, make two other exposures of the identical view at halfway between f8 and f11 and another at f11 and f16. Leave your shutter setting at 1/125th for all.

Shoot an entire roll this manner -- with over and under-exposure -- of typical subjects. Then examine the results side by side with a magnifying glass on a light table. If you like the lighter or darker exposure better than the normal, adjust your meter accordingly. (For the lighter, if the film ASA is 100, decrease to ASA 75; for the darker result, increase the film speed setting to ASA 150.) If you don't notice a difference, leave the ASA setting as recommended.

The same testing procedure can be followed to determine how far a film can be pushed or force-developed and still give satisfactory results. (I routinely push Professional High Speed Ektachrome tungsten Type B film rated at ASA 160 to a very usable ASA 320.)

But these are techniques only for those who take their pictures quite seriously. Shooting for fun, don't take grain seriously; just show your pictures whether the grain shows or not. Q: Your column on plastic slide holders was of great interest to me as I, too, use a large quantity of them. I find them very handy in both transport and storage. The only objection I have is the awful odor that emanates from the holders when new. To dissipate the smell, I spread out the new plastic sheets on tables, floors or whatever, and sometimes hang them up by inserting a paper clip into the ring holes and attaching them on a cord line. A: Thanks for the airing-out tip. I, too, have had some uncomfortable olfactory experiences with the plastic slide pages. One reason, I thinks, is that in the factory they're sealed into plastic, which permits no air-flow. The new ones that I'm using now seem to be relatively odorless. These are the tiploading frosty-back vinyl pages (Stock Tl-20) manufactured by 20th Century Plastics Inc., of 3628 Crenshaw Boulevard, Los Angeles, Calif. 90016.