• Home
  • Download PDF
  • Order CD-ROM
  • Order in Print
Aperture
Image  Sharpness

Photography (Basic) - Introduction to photography and other graphic techniques
Page Navigation
  66    67    68    69    70  71  72    73    74    75    76  
Table 4-1.–How to Control Depth of Field If you want less Use  a  larger  f/stop  (lower  number). Use  a  longer  focal  length  lens. Move  closer  to  the  subject. Use  a  filter  to  reduce  the  amount  of light  allowed  to  be  transmitted  and use a larger f/stop. If you want more Use  a  smaller  f/stop  (higher  number). Use a shorter focal length lens. Back  up  from  the  subject. Use a faster film or a slower shutter speed  and  use  a  smaller  f/stop. Focus  at  the  hyperfocal  distance. f/16 but focusing now at about 16 feet, the depth of field is almost at infinity. Most normal lenses for 35mm cameras  produce  these  maximum  ranges  of  sharpness  at about 16 feet. Focusing any farther from the camera only reduces  foreground  sharpness.  You  must  remember  this point  when  attempting  to  get  the  greatest  possible  depth of field. Lens focal length is also a factor in depth of field. The  shorter  the  lens  focal  length,  the  greater  the  depth of field at a given aperture. In other words, a wide-angle lens provides more depth of field at f/8 than a normal lens,  and  a  normal  lens  provides  more  depth  of  field  at f/8  than  a  telephoto  lens. You know that a small aperture like f/16 provides more  depth  of  field  than  a  wide  aperture  like  f/2.  With experience,  you  can  predict  the  best  aperture  for  the depth of field desired. Even with experience, you do not always have to guess the aperture setting or calculate the hyperfocal distance, near distance, and far distance by using  formulas.  Most  lenses  have  a  depth-of-field  scale to  guide  you  (fig.  4-13).  The  depth-of-field  scale indicates  the  distance  range  from  the  camera  that  the subject(s)  appear  in  acceptably  sharp  focus.  The  depth of field on an SLR is marked between the aperture ring and the focusing scale. Use the depth-of-field scale as follows: 1.  Focus  on  the  subject. 2. Select the f/stop. depth-of-field  scale.  You  may  have  to  estimate the  distances. You  can  see  in  figure  4-13  that  the  lens  is  focused at  a  distance  of  30  feet  with  the  aperture  set  between  f/16 and f/22. You can see from the depth-of-field scale that the depth of field extends from approximately 11 feet to beyond  infinity.  If  the  aperture  is  opened  up  to  f/8,  the depth of field will range from about 16 feet to infinity. At  any  given  aperture,  depth  of  field  is  maximized by  focusing  the  lens  at  the  hyperfocal  distance.  That  is the closest point of acceptable sharp focus shown on the depth-of-field scale when the lens is focused at infinity. When  you  are  changing  the  focus  setting  to  the hyperfocal distance, the zone in front of the subject that is  sharp  is  increased,  and  infinity  is  still  the  farthest  point 3.  Look  at  the  depth-of-field  scale  and  locate  the marks  that  correspond  to  your  chosen  f/stop.  The f/stop  appears  twice,  once  on  either  side  of  the scale  center  line. 4. Read the two distances on the focusing scale that are  adjacent  to  the  two  f/stops  on  the PHC Ron Bayles 302.102 Figure 4-13.–Depth-of-field scale. 4-11







Western Governors University

Privacy Statement
Press Release
Contact

© Copyright Integrated Publishing, Inc.. All Rights Reserved. Design by Strategico.