Skylight Filter A skylight filter adds warmth to a scene recorded on color   transparency   film   by   absorbing   ultraviolet radiation.   It   does   this   by   reducing   the   bluish   cast prevalent in distant scenes and in scenes photographed on heavily overcast days or in open shade. A skylight filter is light pink in color. EXPOSURE  CALCULATION LEARNING   OBJECTIVE:   Identify   the components  used  to  calculate  a  photographic exposure. When you click the shutter, a series of events occur inside  the  camera.  The  shutter  opens  and  closes,  and light  passes  through  the  lens  of  the  camera  onto  the sensitized emulsion (film), forming a latent image. The emulsion  will  eventually  yield  a  record  of  what  the camera saw at the moment of exposure. This series of events  will  yield  a  satisfactory  photograph,  in  a technical sense, only if the exposure was correct. You must compute exposure to make sure that the amount  of  light  reaching  the  sensitive  emulsion  is sufficient  to  record  the  image.  Exposure  depends  on  the sensitivity of the photographic emulsion to light and on the  brightness  reflected  by  the  original  subject.  Because you usually desire to record the whole range of tones between the brightest and darkest parts of the original scene,   you   will   have   to   adjust   your   exposure accordingly. The same exposure can be given to a certain subject by  using  various  combinations  of  lens  openings  and exposure  times  —  a  wide  opening  and  short  time  of exposure may allow the same total amount of light to reach the photographic emulsion as a small opening and along exposure time. At the moment, your consideration of the other factors involved in exposure, such as image movement,  depth  of  field  and  the  use  of  filters,  is unimportant. After you have decided upon the connect total exposure necessary for a given subject at a given time,  you  can  modify  the  lens  opening  and  shutter speeds later as you desire for specific results. Incorrect   exposures   will   ruin   more   of   your photographs than any other technical error, yet accurate exposure is relatively simple. By reading and using the exposure   guides   contained   in   the   film   data accompanying your film, you can expect good results most  of  the  time.  However,  accurate  exposures  using daylight or tungsten light sources can only be obtained by the connect use of an exposure meter. An important factor for you to remember is that no light  meter,  camera,  film  or  manufacturer  can  guarantee the  connect  exposures  that  good  photography  demands. The only guarantees are your awareness and practice of the  exposure  theory  and  practical  meter  techniques. Good  exposure  techniques  are  efficient  and  simple. Your  having  the  knowledge  of  exposure  techniques frees  you  from  the  stumbling  block  of  exposure determination so you can concentrate on taking pictures, and it simplifies the subsequent developing and printing process. THEORY The   term   exposure,  while   having   different meanings  at  different  times,  is  most  often  used  by photographers   to   indicate   a   certain   combination   of shutter speed and lens aperture. In this case, the shutter speed denotes the length of time the shutter is “open,” allowing light to pass through the lens to strike the film. As  stated  earlier,  various  combinations  of  lens aperture and shutter speed can yield the same exposure. The  correct  determination  of  camera  exposure  is  the object  of  all  exposure  tables,  charts,  calculators  and meters. In any given photographic setting a variety of light will  be  reflected,  since  the  brightness  of  various  objects will  reflect  varying  densities  of  light.  Therefore,  the exposure must be adjusted to produce the correct range of  densities. The result of exposure and development of film is very similar in many ways to that of rain falling on a light-colored concrete sidewalk When the rain begins, only a few drops fall. The cement is darkened at only a few spots. As the rain continues, the cement becomes darker  and  darker,  until  it  is  uniformly  wet  and  dark Continued  rain  will  then  cease  to  cause  any  more changes in the color of the cement sidewalk. You have experienced differences in the intensity of rain  showers.  At  high  intensities,  much  water  comes down in a unit period of time, such as one minute. At low intensities, the amount of water is much smaller. As a result, you could get the same total amount of water within  varying  periods  of  time,  according  to  the intensity of the rain. The total amount of rain recorded is equal to its intensity multiplied by the time during which  it  fell.  The  effects  with  light  are  very  similar. Exposure is the amount of light falling on a unit area of the film or on a unit area of photographic paper. The intensity is the amount of light falling on this unit area during  the  exposure  time.  Thus  the  equation  for exposure is as follows: Exposure = Intensity x Time (E = I x T) 11-20