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Shutter speed — Aperture or F-stop — ISO

The rela­tion­ship between shut­ter speed, aper­ture size (f-stop) and ISO (sen­si­tiv­ity of the record­ing material).

The infor­ma­tion in the fol­low­ing sec­tions can be used as a pho­tog­ra­phy primer for any­one with any type of dig­i­tal or film cam­era. How­ever, in order to learn how to take cre­ative pho­tos, you must have a cam­era that you can con­trol. This means a cam­era with which you can choose the shut­ter speed, the f-stop and the ISO. Most dig­i­tal DSLR cam­eras or 35mm film cam­eras (Nikon, Canon, Minolta, Olym­pus Pen­tax etc.) can do this. Although an auto­matic point and shoot cam­era is use­ful for record­ing events, you don’t have as much con­trol over it. It is there­fore not a great cam­era for learn­ing photography.

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Shut­ter speed in photography

The shut­ter, is the part of the cam­era that opens and closes when you press the shut­ter release but­ton. While the shut­ter is open, the scene you’re tak­ing gets passed to the dig­i­tal sen­sor or film where it is recorded. The dura­tion of time that the shut­ter stays open is referred to as the shut­ter speed. Shut­ter speeds are some of the num­bers that you see in the viewfinder of most DSLR (Dig­i­tal Sin­gle Lens Reflex) cam­eras while you’re com­pos­ing your pic­ture. These num­bers range in value from as fast as 1/4000 of a sec­ond or more to as slow as 1 minute or more.The impor­tant thing to remem­ber AND THIS WILL QUICKLY DEVELOP INTO A THEME is that these num­bers work in a pre­cise and pre­dictable man­ner. Let’s say our cam­era meter tells us that the cor­rect expo­sure for our scene is F5.6(F-stop expla­na­tion com­ing up shortly) at 1/2 (of a sec­ond). This means that the next (full) shut­ter speed higher, 1 sec­ond, lets in two times as much light as 1/2 a sec­ond. The next speed, 2 sec­onds, lets in twice as much light as 1 sec­ond. This means that if the cam­era meter says 1 sec­ond, and we ON PURPOSE set the shut­ter speed to 2 sec­onds, extra light will hit the dig­i­tal sen­sor or  film and make the scene too light or over­ex­posed. If the meter says 1 sec­ond and we set it at 1/2 a sec­ond, not enough light will have passed to the dig­i­tal sen­sor or film and the scene will be too dark or underexposed.


An exam­ple of a string of full-unit shut­ter speed num­bers: 1/500, 1/250, 1/125, 1/60, 1/30, 1/15, 1/8, 1/4, 1/2, 1, 2, 4, 8, 15 sec­onds. A shut­ter speed of 1/2 a sec­ond lets in twice as much light as 1/4 of a sec­ond. But it lets in HALF as much light as 1 sec­ond. The rela­tion­ship is the same for every num­ber on the scale. 1/125 lets in twice as much light as 1/250 because it stays open for twice the length of time. It lets in HALF as much light as 1/60 because it closes more quickly. Shut­ter speed choice is depen­dent on the amount of avail­able light as well as mood you want to cre­ate. If you are tak­ing a pic­ture of a water­fall, a fast shut­ter speed like 1/500 of a sec­ond will freeze the scene, but a long shut­ter speed like 1 sec­ond will make the water blur into a soft stream. A good thing to know right up front is that most peo­ple can­not hold a cam­era (with a nor­mal lens [50mm]) steady enough to take a pic­ture at 1/30 of a sec­ond or slower (1/15, 1/8,1/4 etc.) This is because your hands are always mov­ing slightly. At 1/60 of a sec­ond or faster(unless you’re on a vibrat­ing train or in the mid­dle of an earth­quake) the shut­ter opens and closes fast enough to cap­ture the scene with­out blur. IF YOU ARE USING A ZOOM LENS HOWEVER, the camera’s lens is heav­ier,  bulkier and less sta­ble and you will need to use an even faster speed like 1/125 or 1/250 when hand hold­ing the cam­era. The rule of thumb is as fol­lows; 1/the focal length of the lens=the min­i­mum shut­ter speed to use. Using the zoom lens again, if the zoom is an 80-200mm your safest bet is to use 1/80 as the shut­ter speed at the 80mm end and 1/200 or faster at the 200mm end.

These rules apply to hand hold­ing the cam­era. If you affix the cam­era to a tri­pod you can shoot pretty much as slow as you like because you are not mov­ing the cam­era. If the cam­era is on a tri­pod though, and you are shoot­ing a stand­ing per­son, THE SUBJECT IS MOVING SLIGHTLY. So a shut­ter speed of 1/60 of a sec­ond, regard­less of the cam­era lens used would be a safe bet. If the sub­ject is sit­ting still or lying down (mov­ing less) then you might try 1/30 of a sec­ond if the cam­era is on a tri­pod. What if you are tak­ing a pic­ture of a baloney sand­wich? Baloney sand­wiches don’t move (usu­ally). Then you may shoot 1/30, 1/15, 1/8 etc. But which one do you choose? NOW IT’S TIME TO TALK APERTURE SIZE AND DEPTH OF FIELD.

Faster shut­ter speeds(1/60, 1/125 and faster)will freeze a mov­ing sub­ject such as a danc­ing kit­ten. Slow shut­ter speeds(1/15, 1/8 and slower)will not freeze mov­ing sub­jects, and you can use this to your artis­tic advan­tage. Try tak­ing a pic­ture of mov­ing water and watch the beau­ti­ful blur­ring effect result.

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