light  you  can  make  pictures  that  you  could  not  make with other types of lighting. For example, flash may not be appropriate during a change  of  command  ceremony  or  chapel  service.  Not only might the flash disturb the proceedings, but it may not carry far enough to light the subject adequately. Fluorescent Lighting Indoor   scenes   illuminated   by   fluorescent   lights usually   appear   pleasing   and   natural   in   real   life. However, color pictures of these same scenes will often have  an  overall  color  cast  that  makes  them  look  very unnatural. Fluorescent light is deficient in red light and emits primarily blue and green light. Most color pictures made  without  a  filter  under  fluorescent  light  also  are deficient in red and have an overall greenish appearance. When it is used correctly, fluorescent light does have some advantages over other types of available light. A room  illuminated  by  fluorescent  lamps  is  usually brighter   and   more   evenly   lighted   than   a   room illuminated by tungsten lamps. This higher level of light makes it easier to get enough exposure for your existing light  photography  and  helps  record  detail  that  might have been lost in the shadow areas with other types of existing  light. When  you  are  photographing  people,  fluorescent lighting often causes dark shadows under the eyes of the subject. This effect causes the eyes to appear dark and sunk in. Nighttime, Outdoor Pictures 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. The use of short  exposures  emphasizes  well-lighted  areas  by preserving the highlight detail, while the shadow areas become  dark  due  to  underexposure.  Long  exposures help retain the detail of the dark areas, while highlight detail is lost as a result of overexposure. Large,  dark  areas  in  night  scenes  will  make  it difficult   for   you   to   make   accurate   exposure   meter readings  from  your  camera  position.  You  will  get  the best   meter   reading   results   when   you   take   closeup readings of important scene areas. At night you can make color outdoor pictures using either daylight or tungsten-type films. Pictures made on daylight film will have a warm, yellow-red appearance. Those made on tungsten film will have a colder more natural  look.  However,  both  films  provide  pleasing results so it is a matter of personal preference. A good time for you 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. ELECTRONIC  FLASH  LIGHTING In  situations  in  which  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  —  provided  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   film.   Light   from   an   electronic   flash   unit (strobe) is characterized by its softness, short duration and color balance, approximating that of daylight. When you measure the amount of light that actually reaches an objector scene, a numerical value is obtained that can be converted directly into a flash guide number. The  numerical  value  is  the  light  output  rating  of  an e l e c t r o n i c    f l a s h    u n i t    m e a s u r e d    i n    b e am 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. Correct   exposure   with   electronic   flash   depends upon the following four factors: l The power or light output of the flash unit . The ISO speed of the film used l  The  flash-to-subject  distance l  The  tistop  used Shutter  speed  is  not  a  factor  since  the  time  of exposure is governed solely by the duration of the flask. Notice  we  always  speak  of  flash-to-subject distance,  never  camera-to-subject  distances.  With  all types  of  artificial  illumination  (the  same  as  with 11-14