Q.

I recently purchased a second-hand Pentax Spotmatic that is about 15 years old, as a backup to my equally old camera system. According to the former owner, the camera has never been serviced. Would you recommend routine servicing/cleaning even though the camera functions properly?

A.

If it ain't broke, don't fix it!

To back up this opinion, I talked to Pentax representatives, and they agree. Several camera store employees feel the same way and told me that the cost for general cleaning and lubrication of that camera would be between $75 to $100.

Keep shooting. That camera will continue to wear like steel. If you detect problems, the address for the nearest Pentax repair center is: Pentax Corp. Service Dept., 1101 Stewart Ave., Garden City, NY 11530.

Q.

I have a number of black-and-white snapshots, size 2 1/4x3 1/2 and 2 1/4x2 1/4, which I took in Germany in 1948, with a Zeiss Ikon reflex that still works well. The problem is that they are curled up.

Some of these pictures bring back memories, and I would keep them if they can be flattened.

A.

This is not a difficult problem, but it will require some time and effort to solve.

I would take the gentle approach. First, if the prints can be uncurled without cracking, put three or four in a book, then stack several other books on top. Leave them for a week or so. If there's improvement, stack on more weight and try again.

If this fails, you'll have to do some rewashing. There are several things you should buy at the camera store. Pick up a roll or book of blotting paper, a bottle of a product called "Permawash" and a container of print flattening solution. I have had some experience and success with a product called Pakosol.

In your kitchen sink place a small tray (a flat glass baking pan works well) and mix a solution of Permawash. Soak some prints for several hours. This will make them pliable, remove surface dirt and perhaps some of the 40-year-old chemistry. Follow the soaking directions and wash as told.

Next soak it again, this time in the Pakosol, for several hours. Mix as directed because a little of this concentrate goes a long way.

Drain the prints and blot them with that lintless paper. Try letting some of them air dry and dry others between the blotters. Add some weight on top -- books, especially telephone books, work well.

Don't be surprised if you lose the glossy finish; that can't be restored without a high-gloss dryer.

Q.

I have two old functional light meters, one a Weston whose indicator is calibrated in Weston emulsion speeds, and the other a General Electric calibrated in foot candles.

Can I translate these readings into modern ASA ratings?

A.

No, not really. The General Electric is a lighting meter, not an exposure meter and only reads foot candles. The Weston was a great meter, but it's going to be very hard to translate. You should watch the swap meets; someone might have an old book that could give you the answer. I'd also keep a check on Shutterbug magazine. It lists lots of great, old stuff. If any of our readers have any information, we'll pass it along.

Q.

While on a driving vacation to Los Angeles, I tried to take some pictures from our moving car. I wasn't happy with the results. The only way I could have succeeded would have been to stop the car. Is there a certain speed film I should use?

A.

You're on the right track! This is one of the toughest kinds of pictures to take. It can be done but the results are chancey.

If you take your shots out of the side window at 90 degrees to the subject, you will have motion streaks and blur in the area closest to your car. The farther away your subject is, the sharper it will be.

It will indeed help to use a faster film, particularly if you want to use a program mode. The best thing is to use a manual mode and set the shutter speed for as fast as the light will allow. Also be sure to use your fastest lens.

As to lens size, use nothing longer than a 50mm. Telephotos are usually slower and harder to keep steady.

If possible, shoot at a 45-degree angle, or even through the windshield to make subjects more in line with the direction the care is moving. This will reduce the blur.

Fast film, distant subjects, a fast, short lens and reducing the angle will help make this kind of photography worthwhile.

The Maryland Professional Photographers' Association is staging its 1988 Trade Show and Print Exhibition this weekend as part of its 22nd annual convention. The show includes demonstrations and seminars by local and national suppliers of photographic products and services. The print exhibit will feature award-winning portraits, commercial work and creative prints.

All this will be held at the Holiday Inn Crowne Plaza, Rockville Pike, Rockville. No admission charge. Call 926-3056.

Write Carl Kramer c/o The Washington Post, 1150 15th Street NW, DC 20071.