For color slides with fluorescent light, a daylight type of film with the appropriate filter is best. Tungsten film usually produces slides with too much blue or green when made with fluorescent light. As discussed in chapter 3, the use of filters for color photography helps to overcome the deficiency of red light   in   fluorescent   lamps.   Always   consult   the Photo-Lab  Index  for the best film filter combinations to use. Pictures Outdoors at Night Outdoor night scenes usually include large areas of darkness  broken  by  smaller  areas  of  light  from buildings, signs, and streetlights. Pictures of outdoor scenes are quite easy to make because good results are obtainable over a wide range of exposures. Using short exposures emphasizes well-lit areas by preserving the highlight  detail,  while  the  shadow  areas  are  dark because of underexposure. Long exposures help retain the detail of the dark areas, while highlight detail is lost because of overexposure. Large, dark areas in night scenes make it difficult to make accurate exposure meter readings from your camera  position.  The  best  meter  reading  results  are obtained when you take closeup readings of important scene  areas. Color  outdoor  pictures  at  night  can  be  made  on either  daylight  or  tungsten-type  films.  Pictures  made  on daylight  film  have  a  warm,  yellow-red  appearance. Those made on tungsten film have a colder more natural look; however, both films provide pleasing results, so it is a matter of personal preference which you use. A good time to make outdoor night color pictures is just before it gets completely dark. At this time, some rich blue (or even orange) is in the sky. This deep color at dusk gives a dramatic background to your pictures. Neon signs, streetlights, and building lights make bright subjects for your pictures. At night, right after it stops raining and everything is still wet, is another good time to make outdoor pictures. The lights in the scene produce many colorful reflections on the wet pavement, adding interest to what may otherwise be a lifeless, dull picture. Many buildings look rather ordinary in daylight, but at  night,  they  are  often  interestingly  lighted.  Try photographing the hangar at night, with the lights on and the  hangar  doors  open.  Also,  your  ship  at  night, especially a rainy night may make a very striking picture. Outdoor events that take place at night in a sports stadium are usually well-lighted and make excellent subjects for existing light pictures. Most sports stadiums (as well as streets) are illuminated by mercury-vapor lamps that look blue-green in color when compared to tungsten  lamps.  Your  best  color  pictures  made  under mercury-vapor lighting will be shot on daylight color film, although they will appear bluish green because the lights are deficient in red. Tips  for  existing  light  photography  are  as  follows: Carry a flashlight so you can see to make camera settings. If you do not have an exposure meter or cannot get  a  good  reading,  bracket  your  exposure. Focus carefully; depth of field is shallow at the wide  apertures  required  for  existing  light photography. When  you  have  a  scene  illuminated  by  a combination  of  light  sources,  use  the  type  of color film recommended for the predominant light  source. For pictures of fireworks, support your camera on a tripod, focus at infinity, and aim the camera toward the sky area where the display will take place. Open the shutter for several bursts. ELECTRONIC FLASH LIGHTING In  situations  where  there  is  little  or  no  light available, a portable electronic flash unit is an invaluable piece of photographic equipment. With fast films and long exposures, you may be able to shoot existing light pictures, providing your subject remains still long enough. Although you can certainly get better lighting control   with   elaborate   photographic   lights,   the simplicity  and  portability  of  electronic  flash  is unbeatable. Electronic  flash  provides  an  excellent  source  of artificial light for exposing black-and-white and color daylight-balanced film. Light from an electronic flash unit (strobe) is characterized by softness, short duration, and  color  balance,  approximating  that  of  daylight. By  measuring  the  amount  of  light  that  actually reaches an object or scene, you can obtain a numerical value that can be converted directly into a flash guide number. The numerical value is the light output rating of   an   electronic   flash   unit   measured   in   beam candlepower-seconds  (BCPS)  or  more  correctly, effective   candlepower-seconds   (ECPS). Every electronic flash unit is assigned a guide number as a measure of its light output or power. The higher the guide number, the greater the light output. Guide numbers for various film speeds are usually 5-30