Q: All my pictures of people in front of a window are underexposed. I can't understand this because I have a fully automatic camera. What's wrong?

A: The problem very likely is that the light meter averages in the backgraound bright light and the foreground dark area, leading to underexposure of the people in the picture. This problem can happen with any light-metering system when there are extremes of light and dark.

If you have an override on your meter -- that is, a way of locking in the exposure -- then the answer is simple. All you have to do is first move in close to the subject so that the background light is cut out of your viewfinder and take an exposure reading. Then move back to your picture-taking position and use the close-up exposure setting for the picture.

If your camera is fully auto, with no override, a solution is to move your camera position or ask your subjects to move so they're not in front of the brightly lighted area. Another way of handling this problem is to shoot with flash. The flash will light up the foreground subjects and the brightly lighted background will register on its own. This technique can produce very effective indoor-to-outdoor scenes where someone is seated or is standing by a window looking at a sunlit outdoor scene.

The normal flash-distance setting for a shot of this kind would illuminate the figure, and the sunlit background scene will register at the average 1/60th or 1/25th of a second flash-synch shutter setting.

Q: I am interested in the recently introduced plasic filter systems such as Colin, Ambico and others. Although I like the idea, the problem is that even though filter holders fit my lenses, my first-generation Leicaflex camera meters the light externally rather than through the lens, so I'm wondering whether I should anticipate any exposure difficulties.

Also, I would like your opinion on the advantages and disadvantages of this new approach to filtering.

A: I too am intrigued by this filter system that seems to be a way around that endless juggling of filters in the gadget bag. I will be testing this new concept and a future column will have a full report.

Meanwhile, from what I know of the system, you have to read the exposure through the filter when it is on the lens, as there are no filter factors given. These filters were designed for SLR (through-the-lens metering system). With your camera you should be able to place the filter in front of the meter and take a reading, or use another exposure meter right through the filters.

The plastic used for these filters is high-grade polymer called CR-39, a lightweight optical plastic used for eyeglasses and watch crystals since 1940. The material approximates the qualities of optical glass, so you shouldn't have to worry about loss of resolution. CONTEST FOR HIGH SCHOOL STUDENTS: The 1981 Scholastic/Kodak Photo Awards offer many money prizes as well as scholarships for the best portfolios submitted by high-school seniors.

This is a very worthwhile contest for the young camera buff who may be considering a career in photography. Besides the awards, an exhibit of the winners' work will be circulated through the United States. For entry blanks and information, write Scholastic/Kodak Photo Awards, 50 West 44th Street, New York 10036.