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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.

Controlling Your Camera: Apertures Controlling Your Camera: Apertures Presentation Transcript

  • Controlling Your Camera Apertures
  • Apertures have two effects on your photographs:
  • Apertures have two effects on your photographs: They control the depth of field.
  • Apertures have two effects on your photographs: They control the depth of field. And they control how much light reaches your sensor.
  • The depth of field means how much of theshot is in focus.
  • 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.
  • So, what exactly is an aperture?
  • The aperture of yourcamera is controlledby a diaphragm thatopens and closes tolet in differentamounts of light.
  • 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.
  • It operates verymuch like a leafshutter, but youshould not confusethe two.
  • It operates verymuch like a leafshutter, but youshould not confusethe two.Your camera has ashutter and anaperture diaphragm.
  • Cameralenses mayhave manydifferentsizes ofapertures.
  • The diaphragm islocated insideyour lens and iscomposed ofoverlapping metalleaves.
  • The diaphragm islocated inside yourlens and iscomposed ofoverlapping metalleaves.Its movable leavescan be openedwide to let in morelight or closeddown to let in less.
  • On earlycameras theaperture wasadjusted by QuickTime™ and aindividual metal decompressor are needed to see this picture.“stop” platesthat had holesof differentdiameters.
  • 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.
  • There is astandardized,full-stop seriesof numbers onthe f-stop scaleas shown here.
  • The smallernumberscorrespond tothe largerapertures, andadmit the mostlight.
  • Each largernumbered full f-stopadmits half the lightof the previous one.
  • 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.
  • 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.
  • Digital cameras usuallyhave more than just thefull stops available.
  • Here theaperturesare full stopsand have a 2to 1relationship.
  • The hardestthing torememberaboutapertures isthat the higherthe number,the smallerthe aperture.
  • 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).
  • Depth of fieldis the areafrom near tofar in a scenethat isacceptablysharp in aphotograph.
  • As the aperturechanges, so doesthe depth of field.
  • On this lens, thereis a depth-of-fieldscale (many lensesdo not have one)that you can use toestimate the extentof the depth offield.
  • The bottom rowshows the aperture(f-stop).Here it is set at f/2.
  • The middle ringshows the range offocus for each f-stop
  • 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.
  • Only the narrow section marked “b” is in focus.
  • 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.
  • In this case, more of the scene is in focus.
  • Few lenses provide a range ofapertures greater than eight stops. QuickTime™ and a decompressor are needed to see this picture.
  • Lenses are often described as fast or slow. QuickTime™ and a decompressor are needed to see this picture.
  • These terms refer to the width of the maximum aperture for the lens. QuickTime™ and a decompressor are needed to see this picture.
  • 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.
  • 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.
  • Fast lenses are also more expensive than slower lenses. QuickTime™ and a decompressor are needed to see this picture.
  • The key to great photography is learning how to use the shutter and the aperture together.
  • Each combination of aperture (f-stop) and shutter speedgives you the same exposure.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • What combination of aperture and shutter speed doyou guess was used here?
  • A small aperture to get the deep depth of field and a slowshutter speed to capture the motion blur of the guy sweeping.
  • Paul Shambroom, B83 Nuclear Gravity Bombs in Weapons StorageArea, Barksdale Air Force Base, Louisiana, 1995
  • Aperture and shutter speed?
  • Background in focus, so a small aperture, and also a fastshutter speed because no motion blur. Bright daylightmade this combination possible.
  • Sebastiao Salgado, Gold Miners, Serra Pelada, Brazil, 1986
  • How do you think this photo was taken?
  • Camera is attached to one of the roller coaster cars and arelatively slow shutter speed was used.
  • Robert Landau, Untitled, nd.
  • Aperture? Shutter speed?
  • Wide aperture, fast shutter speed.
  • Lou Jones, Women Swimming, 1998
  • Aperture? Shutter speed?
  • Probably a medium aperture and a faster shutter speed.
  • James Nachtwey, Nicaragua, 1982