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.
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