Keep­ing it steady

Andy West­lake ex­plains ev­ery­thing you need to know about im­age sta­bil­i­sa­tion and how to get the best re­sults from your cam­era

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andy West­lake ex­plains ev­ery­thing you need to know about im­age sta­bil­i­sa­tion and how to get the best out of your cam­era

Im­age sta­bil­i­sa­tion has be­come so ubiq­ui­tous and uni­ver­sally ac­cepted as a use­ful tool that it’s easy to for­get it’s be­come a main­stream fea­ture only re­cently. But, now, while no cam­era maker would dream of sell­ing a cam­era kit with­out some form of sta­bil­i­sa­tion ex­cept at bar­gain­base­ment prices, just a decade ago Canon and Nikon were hap­pily shift­ing shelf-loads of DSLRs with un­sta­bilised 18-55mm kit zooms.

Per­haps be­cause of this, there are still a num­ber of myths and misun­der­stand­ings re­gard­ing sta­bil­i­sa­tion, its ben­e­fits and its pit­falls. In this ar­ti­cle I’m go­ing to take a close look at all as­pects of the tech­nol­ogy, so you can bet­ter un­der­stand how it works, what it can and can­not do, and how you can ex­ploit it to get bet­ter pic­tures.


In 1994 Nikon be­came the first com­pany to in­clude op­ti­cal sta­bil­i­sa­tion in a cam­era, in a 38-105mm lens that was built into the Zoom 700VR 35mm film com­pact. How­ever the fol­low­ing year, Canon in­tro­duced the tech­nol­ogy to a wider au­di­ence with the EF 75-300mm f/4.5-5.6 IS USM: the first im­age-sta­bilised lens for SLR cam­eras. At

around £400 it was ex­pen­sive for a con­sumer tele­zoom, and its sta­bil­i­sa­tion sys­tem was con­sid­er­ably less ef­fec­tive than modern ones, bring­ing per­haps two stops of ben­e­fit.

Like most trans­for­ma­tive tech­nolo­gies, im­age sta­bil­i­sa­tion was rather de­rided when it first ap­peared; it was seen as a crutch for poor hand­hold­ing tech­nique that of­fered lit­tle prac­ti­cal ad­van­tage for the price. But it ex­panded the range of light con­di­tions in which pho­tog­ra­phers could shoot hand­held, es­pe­cially given the low- ISO film most of us were us­ing at the time. The Canon lens also in­tro­duced pho­tog­ra­phers to the ben­e­fits of a sta­bilised viewfinder, al­low­ing more ac­cu­rate com­po­si­tion.

Ini­tially, rel­a­tively few lenses in­cluded im­age sta­bil­i­sa­tion, and these were mostly large, ex­pen­sive tele­photo primes. More than a decade passed be­fore the tech­nol­ogy ap­peared in the mass-pro­duced, in­ex­pen­sive kit lenses rou­tinely sold with SLRs.

Canon and Nikon em­braced in-lens op­ti­cal sta­bil­i­sa­tion sim­ply be­cause with film, it was the only prac­ti­cal so­lu­tion. Con­se­quently, third­party lens mak­ers such as Sigma, Tam­ron and Tok­ina also adopted in-lens sta­bil­i­sa­tion to keep their of­fer­ings com­pet­i­tive. How­ever, once dig­i­tal cam­eras started to be­come main­stream an al­ter­na­tive ap­proach emerged, with Mi­nolta de­but­ing in-body sta­bil­i­sa­tion in its Dim­age A1 bridge cam­era of 2003. Sim­i­lar tech­nol­ogy has since found its way into mod­els from Pen­tax, Olym­pus, Sony and Pana­sonic.

While pho­tog­ra­phers have spent a lot of time ar­gu­ing over the rel­a­tive mer­its of these two ap­proaches, it turns out that their strengths are ac­tu­ally com­ple­men­tary. So most re­cently we’ve seen Pana­sonic, Sony and Olym­pus evolve hy­brid sys­tems that com­bine the best of in-lens and in-body sta­bil­i­sa­tion. This ap­proach gives as­ton­ish­ingly ef­fec­tive re­sults, with Pana­sonic and Olym­pus pro­vid­ing the cur­rent state- of-the-art tech­nol­ogy.

What does IS do?

When­ever you’re hand­hold­ing a cam­era or lens, you can never keep it com­pletely steady. In­stead, the pre­cise an­gle the cam­era is point­ing will be con­tin­u­ally chang­ing, as your mus­cles work to coun­ter­act its weight. If this move­ment is suf­fi­ciently large dur­ing the course of the ex­po­sure, then your im­ages will turn out blurred.

Im­age-sta­bil­i­sa­tion sys­tems use gyro sen­sors to mea­sure these cam­era move­ments that cause im­age blur­ring. Op­ti­cal sys­tems then move a group of el­e­ments within the lens up-and- down and side-to-side to com­pen­sate, so that the im­age is pro­jected sta­bly onto the film or sen­sor. In-body sys­tems move the im­age sen­sor it­self to track the shak­ing im­age; as well as mov­ing up-and­down or side-to-side, the sen­sor can be ro­tated around the lens’s op­ti­cal axis.

It’s cru­cial to un­der­stand that IS doesn’t af­fect im­age blur­ring from sub­ject mo­tion at slow shut­ter speeds. So it’s of lit­tle ben­e­fit if you need to keep mov­ing ob­jects sharp; on the other hand it’s gen­uinely use­ful when you want to ex­ploit mo­tion blur for artis­tic ef­fect.

Axes of evil

You’ll of­ten see im­age-sta­bil­i­sa­tion sys­tems de­scribed in terms of the num­ber of axes of shake they can coun­ter­act. In-lens sys­tems are al­most in­vari­ably 2-axis: they cor­rect up- down and left-right an­gu­lar move­ments (pitch and yaw). In most sit­u­a­tions these are by far the big­gest cause of blur, so 2-axis sta­bil­i­sa­tion works per­fectly well for most pho­tog­ra­phy.

How­ever dur­ing long- ex­po­sure shoot­ing, an­other type of cam­era move­ment be­comes im­por­tant, in the form of ro­ta­tion around the lens axis (or roll). There’s noth­ing

in-lens sys­tems can do to com­bat this, but in-body sys­tems can cor­rect it by ro­tat­ing the sen­sor in the op­po­site di­rec­tion. This means 3-axis in-body sys­tems can be more ef­fec­tive with slow shut­ter speeds, par­tic­u­larly when you’re shoot­ing with widean­gle lenses.

For close- up pho­tog­ra­phy, there’s an­other prob­lem. At high sub­ject mag­ni­fi­ca­tions, move­ment of the lens’s en­trance pupil a frac­tion of a mil­lime­tre up­wards or side­ways rel­a­tive to the sub­ject can re­sult in vis­i­ble blur­ring. This can be ad­dressed by both in-lens and in-body sys­tems, but rel­a­tively few lenses at­tempt to deal with it. How­ever a few of Canon’s macro lenses in­clude the firm’s ‘Hy­brid IS’ that pro­vides 4-axis cor­rec­tion. In-body 5-axis sys­tems can also cor­rect for this mo­tion.

Some read­ers may have re­alised that log­i­cally, there’s a sixth ‘axis’, which is a back-and-forth move­ment of the cam­era rel­a­tive to the sub­ject. How­ever this can only be com­pen­sated by con­tin­u­ous aut­o­fo­cus. Cam­era and lens man­u­fac­tur­ers gen­er­ally like to tell you how ef­fec­tive their sta­bil­i­sa­tion sys­tems are, and the CIPA stan­dard of test­ing now used should en­sure that these quoted num­bers are com­pa­ra­ble be­tween dif­fer­ent firms. You’ll see word­ing along the lines of ‘the op­ti­cal sta­bil­i­sa­tion de­liv­ers four stops ben­e­fit’, which es­sen­tially means that you’ll be able to use shut­ter speeds four stops slower than would be oth­er­wise pos­si­ble. How­ever, this means you first need to know what shut­ter speed you could safely use with­out IS.

To de­fine a ‘safe’ shut­ter speed at which im­ages shouldn’t be blurred due to hand­shake, pho­tog­ra­phers have tra­di­tion­ally used the ‘1/fo­cal length’ rule of thumb. This sug­gests that in or­der to get sharp im­ages, you need to shoot at speeds of at least 1/50sec with a 50mm lens, or 1/25sec with a 24mm lens, or 1/100sec with a 100mm lens, and so on. This as­sumes you’re us­ing a full-frame cam­era; oth­er­wise, you’ll need to take the crop fac­tor into ac­count. So with that 50mm lens, you would need at least 1/80sec on an APS- C cam­era or 1/100sec on a Mi­cro Four Thirds model.

In re­al­ity, this is an overly sim­ple way of look­ing at things. Cam­era shake is ran­dom, mean­ing it doesn’t af­fect ev­ery pic­ture in the same way even when they’re shot iden­ti­cally. So if you take five shots at 1/50sec with a 50mm (equiv­a­lent) lens, a cou­ple might be pin-sharp, one might be dis­tinctly blurred, and the oth­ers some­where in be­tween. Drop the shut­ter speed to 1/25sec and you could still get one or two us­able shots out of five. This ran­dom na­ture means that there’s ac­tu­ally no hard cut- off point for a safe shut­ter speed where pic­tures are ‘sharp’ not ‘blurred’.

What’s more, the rule as­sumes that you al­ways get the same de­gree of shake, re­gard­less of the cam­era or lens you’re us­ing. But there’s a world of dif­fer­ence be­tween hand­hold­ing an 18-55mm kit zoom that weighs 200g and a 1.5kg 70-200mm f/2.8. In gen­eral, as your lenses get larger and heav­ier, you’ll need to err to­wards se­lect­ing in­creas­ingly higher shut­ter speeds than the rule might sug­gest. Other fac­tors can also af­fect shake; for ex­am­ple it’s eas­ier to keep a cam­era steady if it has a de­cent hand­grip. Equally, low tem­per­a­tures, high winds or even how much cof­fee you’ve been drink­ing can all in­crease shake. Even the an­gle at which you’re point­ing the cam­era will have an ef­fect; you’ll get less-sharp shots point­ing your cam­era up or down, com­pared to hold­ing it level.

What’s more, if you want to get pixel-sharp im­ages from a modern sen­sor of 24MP or

‘If you ex­ploit im­age sta­bil­i­sa­tion fully, it’s pos­si­ble to get sharp im­ages hand­held at very slow shut­ter speeds’

more, you’ll need to use faster shut­ter speeds again. Per­son­ally I’d err to­wards choos­ing shut­ter speeds twice as fast to be sure of get­ting gen­uinely sharp shots, mean­ing I’d use 1/100sec with a 50mm equiv­a­lent lens.

What this all means is that if a sys­tem prom­ises four stops of sta­bil­i­sa­tion with a 50mm equiv­a­lent fo­cal length, I wouldn’t take that as mean­ing I should al­ways get sharp shots at 1/3sec (i.e. four stops slower than 1/50sec). In­stead I’d ex­pect to be able to get most of my shots de­cently sharp at 1/6sec, with a rea­son­able chance of get­ting some sharp pic­tures at slower shut­ter speeds, es­pe­cially if I shoot a few du­pli­cates. Like­wise, with a 70-200mm f/2.8 giv­ing four stops of sta­bil­i­sa­tion, at the 200mm end I’d ex­pect to need 1/30sec at least to be con­fi­dent of get­ting sharp re­sults.

That said, if you ex­ploit im­age sta­bil­i­sa­tion fully, it’s pos­si­ble to get sharp im­ages hand­held at very slow shut­ter speeds. This is par­tic­u­larly the case when you’re able to sup­port the cam­era and lens by lean­ing on a wall or rail­ing, or us­ing a mono­pod. You’ll get best re­sults when you also prac­tise good hand­hold­ing tech­nique: adopt a com­fort­able shoot­ing stance, hold the cam­era to your eye, and

sup­port the lens with your free hand. In such cases you might be sur­prised by just how slow you can go; with the lat­est cam­eras and lenses I reg­u­larly at­tempt hand­held shots at shut­ter speeds of up to 1 sec­ond with wider lenses, and can of­ten get a sharp im­age out of four or five at­tempts.

As usual, the best thing to do is to carry out some tests to see what works for you. Shoot a de­tailed test scene at a range of shut­ter speeds, tak­ing five shots at each. Ex­am­ine the re­sul­tant files on your com­puter and de­ter­mine which meet your stan­dards for sharp­ness. For op­ti­cally sta­bilised zooms, you might like to test at the two ex­tremes of the zoom range; how­ever I’ve found that in-lens sys­tems tend to be equally ef­fec­tive at all fo­cal lengths. The same cer­tainly isn’t true for in-body IS, though, which tends to be most ef­fec­tive with wider lenses. So for these you need to test with a range of dif­fer­ent lenses. In-lens ver­sus in-body IS With in-lens sta­bil­i­sa­tion sys­tems be­ing used by the big two cam­era man­u­fac­tur­ers, Canon and Nikon, it might be tempt­ing to as­sume that it’s a tech­ni­cally su­pe­rior ap­proach to solv­ing the prob­lem of hand-shake. But as I’ve al­ready ex­plained, it’s not that sim­ple – the firms’ adop­tion of op­ti­cal sta­bil­i­sa­tion was ini­tially dic­tated by the re­quire­ments of film SLRs.

How­ever, op­ti­cal sta­bil­i­sa­tion does have some very sig­nif­i­cant ad­van­tages. It’s more power ef­fi­cient and ef­fec­tive with tele­photo lenses, be­cause a rel­a­tively small move­ment of the cor­rec­tive op­ti­cal group is needed to com­bat blur. By con­trast, in-body sys­tems sim­ply can’t move the im­age sen­sor far enough, quickly enough to com­pen­sate for shake with lenses of around 300mm or longer. Yet it’s pre­cisely these op­tics that ab­so­lutely need sta­bil­i­sa­tion to be us­able hand­held – it’s barely pos­si­ble to com­pose pic­tures ac­cu­rately with ul­tra-tele­pho­tos oth­er­wise.

Op­ti­cal sta­bil­i­sa­tion can also be in­cor­po­rated rel­a­tively eas­ily into small, cheap zooms, whereas in-body IS gen­er­ally adds sub­stan­tial cost to a cam­era, along with a lit­tle ex­tra bulk. With SLRs, op­ti­cal IS also sta­bilises the im­age that’s pro­jected onto the sep­a­rate aut­o­fo­cus sen­sor, the­o­ret­i­cally re­sult­ing in more ac­cu­rate and re­li­able AF com­pared to us­ing in-body IS. With mir­ror­less cam­eras, of course, in-body IS sta­bilises both the viewfinder im­age and the AF sys­tem.

On the other hand, with in-lens IS, you have to pay for the priv­i­lege ev­ery sin­gle time you buy a lens. Op­ti­cal IS has also proven dif­fi­cult to in­clude in cer­tain lens types, mean­ing that there are rel­a­tively few im­age-sta­bilised widean­gle zooms and fast primes on the mar­ket. In con­trast, if your cam­era has in-body IS, ev­ery lens you can use au­to­mat­i­cally be­comes sta­bilised.

It’s worth not­ing that not all in-body IS sys­tems are cre­ated equal. In­stead, smaller sen­sors have an in­her­ent ad­van­tage over larger ones: not only is the sen­sor unit lighter, which means it takes less power to move, but it also has to travel a shorter dis­tance to achieve

the same sta­bil­is­ing ef­fect. As a re­sult, Mi­cro Four Thirds cam­eras tend to of­fer more ef­fec­tive sta­bil­i­sa­tion, and con­tinue to work with longer lenses, com­pared to APS- C or full-frame mod­els.

Dual IS sys­tems

With in-body IS ex­celling in those ar­eas where in-lens IS falls down, it’s no real sur­prise that some cam­era man­u­fac­tur­ers have started to use them hand in hand. Sony, Olym­pus and Pana­sonic all now of­fer some kind of Dual IS sys­tem in which in-body and in-lens sta­bil­i­sa­tion sys­tems work to­gether. For ex­am­ple, if you were to mount an op­ti­cally sta­bilised lens on a Sony mir­ror­less model with in-body sta­bil­i­sa­tion, then the lens’s op­ti­cal cor­rec­tion is used to com­bat tilt and yaw, while the sen­sor re­duces blur from roll around the lens axis. Olym­pus’s Sync IS goes a step fur­ther and uses both the in-lens and in-body sys­tems to­gether to cor­rect larger tilt-and-yaw move­ments.

Hy­brid sys­tems are the most ef­fec­tive of all, but are still some­what in their in­fancy. Olym­pus’s Sync IS sys­tem is stag­ger­ingly ef­fec­tive with a spec­i­fied 6.5 stops sta­bil­i­sa­tion, mean­ing its flag­ship OM- D E- M1 Mark II mir­ror­less cam­era al­lows hand­held shoot­ing at shut­ter speeds longer than a sec­ond with the M. Zuiko Dig­i­tal ED 12-100mm f/4 IS Pro lens. But the firm only of­fers one other op­ti­cally sta­bilised lens, in the shape of the M. Zuiko Dig­i­tal ED 300mm f/4 IS Pro. Mean­while, Pana­sonic has a much larger range of sta­bilised lenses, but only its most re­cent bod­ies in­clude in-body sta­bil­i­sa­tion that works as part of its Dual IS sys­tem. Frus­trat­ingly, Olym­pus’s and Pana­sonic’s hy­brid sys­tems aren’t cross- com­pat­i­ble, so if you use a Pana­sonic lens on an Olym­pus cam­era (or vice versa) you can use ei­ther the op­ti­cal or in-body IS, but not both to­gether.

IS modes

Usu­ally you want to cor­rect blur from all pos­si­ble axes of cam­era move­ment. But when you’re pan­ning the cam­era to track a mov­ing sub­ject, the IS sys­tem can fight against what you’re try­ing to do. So most cam­eras and lenses have spe­cific modes that turn off sta­bil­i­sa­tion in the di­rec­tion you’re mov­ing the cam­era. Most modern sys­tems also at­tempt to de­tect this kind of cam­era move­ment and au­to­mat­i­cally switch to pan­ning mode.

Cer­tain lenses also of­fer ad­di­tional sta­bil­i­sa­tion modes. For ex­am­ple, many Nikon lenses have an ‘Ac­tive’ set­ting that’s de­signed for use when shoot­ing from a mov­ing ve­hi­cle. Es­sen­tially, this al­lows the op­tics to move fur­ther so they can cor­rect larger shak­ing mo­tions of the lens. How­ever, this in­creased de­cen­tring can bring a sharp­ness penalty.

Canon and Tam­ron have also re­cently in­tro­duced an­other IS mode. While Mode 1 is for nor­mal use and Mode 2 for pan­ning, Mode 3 doesn’t sta­bilise the viewfinder im­age and only ac­ti­vates IS at the point of ex­po­sure. In prin­ci­ple this gives the great­est sta­bil­i­sa­tion.

Creative uses of IS

Be­cause IS first ap­peared on tele­photo lenses, it’s tempt­ing to think that it’s not re­ally needed with other lens types. Af­ter all you can safely shoot at slower shut­ter speeds with widean­gle lenses, while large-aper­ture primes let you use higher shut­ter speeds to avoid hand-shake.

This, how­ever, rather misses the point. Im­age sta­bil­i­sa­tion is use­ful when­ever you might want to shoot with a slow shut­ter speed hand­held, re­gard­less of the lens you’re us­ing. Quite sim­ply, it lets you use the low­est pos­si­ble ISO for the best im­age qual­ity while keep­ing shut­ter speeds high enough to avoid un­wanted mo­tion blur. You’ll cer­tainly want sta­bil­i­sa­tion if you shoot video hand­held, too.

You can also ex­ploit sta­bil­i­sa­tion for more creative uses. Typ­i­cally, you might wish to use a small aper­ture for ex­tended depth of field. But you could also use a long shut­ter speed for de­lib­er­ate mo­tion blur, with­out hav­ing to set up a tri­pod. Al­ter­na­tively in the low-light, high- con­trast sit­u­a­tions that you’ll come across when shoot­ing about town at night, sta­bil­i­sa­tion can en­able you to ex­pose to main­tain high­light de­tails, while also us­ing low ISO set­tings to ex­ploit their greater dy­namic range in or­der to pull out de­tails in the darker ar­eas of the im­age.

Im­age sta­bil­i­sa­tion can be built into the lens or cam­era body. Some sys­tems use both at the same time

Here I used a long shut­ter speed hand­held for creative blur Sony Al­pha 7 II, FE 24-70mm f/4 OSS ZA at 27mm 1sec at f/10, ISO 50

IS also lets you use smaller aper­tures Canon EOS 5D Mk IV, Tam­ron 70-200mm f/2.8 G2 at 200mm, 1/30sec at f/16, ISO 100

Above: Sta­bil­i­sa­tion is ideal for shoot­ing hand­held at night Right: Here I was able to use a low ISO with­out sac­ri­fic­ing depth-of-field Olym­pus OM-D E-M10 Mark III, 14-42mm f/3.5-5.6 at 42mm, 1/10sec at f/6.3, ISO 200 Olym­pus OM-D E-M5 Mark II, 12-40mm f/2.8 at 19mm, 1/5sec at f/2.8, ISO 200

In Olym­pus’s Sync IS, the in-lens and in-body sys­tems work to­gether to com­bat pitch and yaw mo­tion

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