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Controlling Your Camera: Apertures
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Controlling Your Camera: Apertures

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Basic instructions for adjusting your camera's aperture.

Basic instructions for adjusting your camera's aperture.

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  • Compact digital cameras usually have even less than SLR’s.
  • This is because more of the lens is composed of precision glass.
  • Go through this slowly.
  • We are going to look at three exposures that allow the same amount of light to reach the sensor, but that the different shutter speeds and apertures make very different photos.
  • Small aperture Slow shutter speed to show motion blur
  • Small aperture Fast shutter speed - no motion blur
  • (camera is attached or held steady on the coaster and a relatively slow shutter speed used)
  • (wide aperture, fast shutter speed)
  • Definitely a fast shutter speed and medium to wide area in focus, so probably a medium to small aperture.

Transcript

  • 1. Controlling Your Camera Apertures
  • 2. Apertures have two effects on your photographs:
  • 3. Apertures have two effects on your photographs: They control the depth of field.
  • 4. Apertures have two effects on your photographs: They control the depth of field. And they control how much light reaches your sensor.
  • 5. The depth of field means how much of theshot is in focus.
  • 6. The depth of field means how much of theshot is in focus.A large aperture has a shallow depth of fieldand a small aperture has a deep depth offield.
  • 7. So, what exactly is an aperture?
  • 8. The aperture of yourcamera is controlledby a diaphragm thatopens and closes tolet in differentamounts of light.
  • 9. The diaphragmof your cameraworks much likethe pupil of the QuickTime™ and a decompressorhuman eye, are needed to see this picture.opening andclosing to adjustthe amount oflight thatreaches theeye.
  • 10. It operates verymuch like a leafshutter, but youshould not confusethe two.
  • 11. It operates verymuch like a leafshutter, but youshould not confusethe two.Your camera has ashutter and anaperture diaphragm.
  • 12. Cameralenses mayhave manydifferentsizes ofapertures.
  • 13. The diaphragm islocated insideyour lens and iscomposed ofoverlapping metalleaves.
  • 14. The diaphragm islocated inside yourlens and iscomposed ofoverlapping metalleaves.Its movable leavescan be openedwide to let in morelight or closeddown to let in less.
  • 15. On earlycameras theaperture wasadjusted by QuickTime™ and aindividual metal decompressor are needed to see this picture.“stop” platesthat had holesof differentdiameters.
  • 16. The term stopis still used torefer to theaperture size,and a lens is QuickTime™ and a decompressor are needed to see this picture.said to be“stopped down”when the size ofthe aperture isdecreased.
  • 17. There is astandardized,full-stop seriesof numbers onthe f-stop scaleas shown here.
  • 18. The smallernumberscorrespond tothe largerapertures, andadmit the mostlight.
  • 19. Each largernumbered full f-stopadmits half the lightof the previous one.
  • 20. Each largernumbered full f-stopadmits half the lightof the previous one.A lens that is set atf/4 admits half asmuch light as oneset at f/2.8.
  • 21. Notice that f-stops have the same half or double relationship thatfull-stop shutter-speed settings do. QuickTime™ and a decompressor are needed to see this picture.
  • 22. Digital cameras usuallyhave more than just thefull stops available.
  • 23. Here theaperturesare full stopsand have a 2to 1relationship.
  • 24. The hardestthing torememberaboutapertures isthat the higherthe number,the smallerthe aperture.
  • 25. The easiest way toremember is toequate the numbersto the amount of thescene that is in focus: ie. f/2.8 (2.8 feet totalin focus) will have ashallower depth offield than f/22 (22total feet in focus).
  • 26. Depth of fieldis the areafrom near tofar in a scenethat isacceptablysharp in aphotograph.
  • 27. As the aperturechanges, so doesthe depth of field.
  • 28. On this lens, thereis a depth-of-fieldscale (many lensesdo not have one)that you can use toestimate the extentof the depth offield.
  • 29. The bottom rowshows the aperture(f-stop).Here it is set at f/2.
  • 30. The middle ringshows the range offocus for each f-stop
  • 31. And the upper ringshows the actualdistance within whichthe lens is focused.The point of focus inthis depth of field is atabout 7 feet from thecamera lens.
  • 32. Only the narrow section marked “b” is in focus.
  • 33. Here the aperture is set tof/16.Looking at the guide, youcan see that the depth offield at this aperture is fromabout 5 feet to 13 feet fromthe lens.Everything between thosetwo points is in focus.
  • 34. In this case, more of the scene is in focus.
  • 35. Few lenses provide a range ofapertures greater than eight stops. QuickTime™ and a decompressor are needed to see this picture.
  • 36. Lenses are often described as fast or slow. QuickTime™ and a decompressor are needed to see this picture.
  • 37. These terms refer to the width of the maximum aperture for the lens. QuickTime™ and a decompressor are needed to see this picture.
  • 38. A lens that opens to f/1.4 opens widerand is said to be faster than one that opens only to f/2. QuickTime™ and a decompressor are needed to see this picture.
  • 39. Faster lenses allow you to shootmore easily in low light or at faster shutter speeds. QuickTime™ and a decompressor are needed to see this picture.
  • 40. Fast lenses are also more expensive than slower lenses. QuickTime™ and a decompressor are needed to see this picture.
  • 41. The key to great photography is learning how to use the shutter and the aperture together.
  • 42. Each combination of aperture (f-stop) and shutter speedgives you the same exposure.
  • 43. Each combination of aperture (f-stop) and shutter speedgives you the same exposure.This means that each combination allows the sameamount of light to reach your camera’s sensor.
  • 44. However, this does not mean that eachexposure makes the same photograph.Remember that the aperture andshutter speed affect the motion blur andthe depth of field.
  • 45. In this example, a small aperture is used, soa longer exposure time is required. Thislonger shutter speed gives the photo somemotion blur. And the picture has a deepdepth of field.
  • 46. Here the same shot has been exposed with a largeraperture and a shorter shutter speed. Less of thebackground is in focus because there is only amoderate depth of field. But the quicker shutterspeed catches more of birds and less of the motion.
  • 47. In this final exposure, the scene is captured with alarger aperture and a very fast shutter speed. Thusthere is a very shallow depth of field (less of the shotis in focus). But the fast shutter speed captures thebirds entirely without any motion blur.
  • 48. What combination of aperture and shutter speed doyou guess was used here?
  • 49. A small aperture to get the deep depth of field and a slowshutter speed to capture the motion blur of the guy sweeping.
  • 50. Paul Shambroom, B83 Nuclear Gravity Bombs in Weapons StorageArea, Barksdale Air Force Base, Louisiana, 1995
  • 51. Aperture and shutter speed?
  • 52. Background in focus, so a small aperture, and also a fastshutter speed because no motion blur. Bright daylightmade this combination possible.
  • 53. Sebastiao Salgado, Gold Miners, Serra Pelada, Brazil, 1986
  • 54. How do you think this photo was taken?
  • 55. Camera is attached to one of the roller coaster cars and arelatively slow shutter speed was used.
  • 56. Robert Landau, Untitled, nd.
  • 57. Aperture? Shutter speed?
  • 58. Wide aperture, fast shutter speed.
  • 59. Lou Jones, Women Swimming, 1998
  • 60. Aperture? Shutter speed?
  • 61. Probably a medium aperture and a faster shutter speed.
  • 62. James Nachtwey, Nicaragua, 1982