ISO: DARK MAT­TERS

HERE IS G&G’S 3-PART SE­RIES ON THE THREE PIL­LARS OF PHO­TOG­RA­PHY. WE START WITH LIGHT SEN­SI­TIV­ITY, OR ISO, IN THIS IS­SUE, AND WILL COVER SHUT­TER SPEED AND APER­TURE IN THE COM­ING EDI­TIONS.

Gadgets and Gizmos (India) - - DIGITAL LIFE - BY TUSHAR KAN­WAR

There’s a fa­mous say­ing in pho­tog­ra­phy cir­cles that buy­ing a fancy new DSLR cam­era doesn’t make you a bet­ter pho­tog­ra­pher, it only makes you a new cam­era owner. More so, if all you do is keep the cam­era on full Auto mode for all your shots. To truly push your­self and get the most out of your cam­era, you need to un­der­stand the three pil­lars of pho­tog­ra­phy: shut­ter speed, aper­ture and sen­si­tiv­ity. In the first of a three-part se­ries, we look at sen­si­tiv­ity (ISO) and how even a ba­sic mas­tery of this oft-over­looked con­trol can dra­mat­i­cally im­prove your pho­tos.

WHY DOES ISO MAT­TER?

At its most ba­sic, cam­era ISO is the level of sen­si­tiv­ity of your cam­era im­age sen­sor to avail­able light. When you be­gin fid­dling around with your cam­era’s ISO set­ting, you’ll notice it is mea­sured by num­bers along the ISO scale, start­ing typ­i­cally at ISO 100 and dou­bling from this point to the limit of your cam­era’s ca­pa­bil­i­ties: 100, 200, 400, 800, 1600, etc. Now, the lower the ISO num­ber, the less sen­si­tive the sen­sor is to the light, and so the more the light re­quired for a proper ex­po­sure. That ex­tra light usu­ally comes by way of a slower shut­ter speed which al­lows more light to fall on the sen­sor, which means that low ISOs like 100 or 200 are used in bright sit­u­a­tions or when you can sta­bilise

the cam­era on a tri­pod.

Now, what if you don’t have a lot of light but still need a fast shut­ter speed to cap­ture mo­tion? You can then choose to bump up the sen­si­tiv­ity of the sen­sor. Re­mem­ber the rule of thumb: each time you dou­ble the ISO (say, from 200 to 400), the cam­era needs only half as much light for the same ex­po­sure. So if you find that a par­tic­u­lar shut­ter speed is not cap­tur­ing mo­tion fast enough—chil­dren play­ing in­doors, for in­stance—you can shoot with a shut­ter speed twice as fast if you go from ISO 200 to ISO 400.

IS THERE A DARK SIDE TO ISO?

If this sounds too good to be true, there is a trade­off—higher ISOs lead to a grainier im­age or a de­crease in qual­ity, re­ferred to as “noise”. This make the im­age look sort of chunky and low-on-de­tail. Bear in mind, one sign­f­i­cant de­ter­mi­nant of the amount of dig­i­tal noise at high ISOs is the size of the sen­sor and, there­fore, the size of in­di­vid­ual pix­els used on the sen­sor. Larger pix­els re­sult in less noise than smaller ones. Since DSLRs usu­ally pack in larger sen­sors than av­er­age com­pact cam­eras, they per­form much bet­ter—which trans­lates as turn­ing out bet­ter im­ages with lesser noise at higher ISOs.

WHAT ISO DO I USE AND WHEN?

If you can af­ford to, al­ways try and stick to the “base ISO”, which is typ­i­cally the low­est ISO num­ber of the sen­sor that pro­duces the best im­age qual­ity with­out adding noise. For most Nikon and Canon cam­eras, that’s in the range of ISO 100200. Within this range, your pho­tos will have the best de­tails, and you need not touch that dial to boost ISO if you’re shoot­ing in day­light. ISO 200-400 should be cho­sen for slightly darker con­di­tions, such as a cloudy day, in the shade or brightly lit in­doors. The 400-800 range helps in in­door shots with­out too bright a lighting. This range works re­ally well if you shoot with a flash, giv­ing you a more even ex­po­sure with­out loss of de­tail.

Ranges higher than 800 are great for dimly lit events such as live per­for­mances where flash is not al­lowed and tripods may not be an op­tion, or if you sim­ply don’t want to “blow out” the sub­ject as of­ten hap­pens when you use the flash. Pro­ceed with cau­tion with ISO 1600 and above as just the sheer abil­ity to cap­ture the shot may not be worth the re­sul­tant noise. Av­er­age DSLR cam­eras start fal­ter­ing at ISO 1600-3200, so it’s best to ex­per­i­ment at these set­tings be­fore shoot­ing. In gen­eral, most sit­u­a­tions that ne­ces­si­tate high ISOs are when you need to shoot fast ac­tion in low light, and you’ve run out of op­tions in terms of shut­ter speed/aper­ture.

WHAT IF I DON’T LIKE THE FALL­OUT OF HIGH ISO?

You don’t have to shoot at higher ISOs— the al­ter­na­tive is to get more light, ei­ther ar­ti­fi­cial or nat­u­ral, or to se­lect a slower shut­ter speed and prop the cam­era on some­thing sta­ble (like a ta­ble or a tri­pod). You could choose a wider aper­ture (we’ll cover these in the com­ing months). And re­mem­ber, if you start ex­per­i­ment­ing with the ISO set­tings, get into the habit of al­ways check­ing what ISO you’ve cho­sen when you switch on the cam­era. Many pho­tog­ra­phers have shot an en­tire event to find out that they’d for­got­ten to check what ISO set­ting they’d used the last time they used their cam­eras. There’s noth­ing worse than think­ing you’re shoot­ing at an ISO of 100 only to find you had for­got­ten to switch it back from 1600.

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1600

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800

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400

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100 IM­AGES COUR­TESY: flickr users pock­et­p­cian, xshamethe­strongx, doom­godyuan and 72213316@N00

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