Most of us put our cameras away at the end of a sight-seeing day. Since the daylight is over, we feel, so are the opportunities for pictures, right? Wrong.

Many of my best pictures were taken after dark. Dusk, just when the lights are turned on, is the very best time to take those combination daylight and artificial light photos. Unfortunately, this may be just the time when you're packing up your gear and looking forward to that refreshing drink back in the hotel. If you will just put off that anticipated relaxation a short while, you can come up with some photos that will draw ohs and ahs at your next slide show.

Color photos taken at this time will have indigo blue skies pubctuated by the warm oranges and reds of the incandescent lights.

The best way to plan these dusk pictures is to scout locations as you shoot during the day. Remember where there is an interesting statue or a building that has lamps on or around it. Then return to the site at sunset.

The best part of taking dusk pictures is that determining exposure is easy. If you have a camera with a built-in meter, simply expose as the meter indicates. If you don't have a meter, use the B (bulb) setting on your camera and make an exposure of a second by depressing the shutter on the count of one and releasing it on the count of two. For this method set your f/stop at f/5.6 for slow films of ASA 64 or less, and stop down to f/16 for the faster ones, with an ASA rating of 200 or more.

If all you have is a simple box camera that has a "B" setting but no f/stops, the one-second exposure will do with the average color or black-and-white film.

The real trick to taking these dusk pictures lies not in the camera but in the eye. You have to decide by sight when the turn-on lights have the right intensity in proportion to what day-light still exists. The way to make this determination is to use an old artist's technique. Squint your eyes so you are just barely seeing the detail in your scene. Shoot the picture after the lights are turned on but before it gets so dark that you can't see daylight detail through your half-closed eyes.

You should have a tripod for these shots, but if you don't, don't despair. Just brace your camera by holding it firmly with one hand against a pole or tree trunk or on top of a fence railing.

If you have a cable release, use it to trip the shutter. If you don't have one, apply finger pressure gently and lease just as slowly.