Techniques for Setting Manual Exposure

The first step in becom­ing pro­fi­cient at any of the man­u­al expo­sure tech­niques dis­cussed below is by famil­iar­iz­ing your­self with the quick and pre­cise set­ting and adjust­ment of your camera’s shut­ter speed, aper­ture, and ISO val­ues. The sec­ond step is learn­ing to adjust your camera’s meter­ing modes. The remain­der of this guide will assume you’re com­fort­able with both. The third step is to remem­ber every­thing you have learned about the aes­thet­ic and tech­ni­cal aspects of the shut­ter, aper­ture, and ISO, and put that knowl­edge into prac­tice. Last­ly, it’s impor­tant to under­stand that both this and the fol­low­ing sec­tion are con­cerned with man­u­al expo­sure, not man­u­al focus­ing. Too often, stu­dents and oth­er begin­ners gain the impres­sion that man­u­al mode requires man­u­al every­thing, which con­tributes to their feel­ings of intim­i­da­tion. For­tu­nate­ly, they are incor­rect; in fact, the only con­tem­po­rary cam­era sys­tems for which this is true is Leica’s M-series, which is inca­pable of auto­mat­ic or semi-auto­mat­ic focus­ing.

Is manual exposure necessary?

Mem­o­rable pho­tographs, espe­cial­ly land­scapes, are often the result of light­ing con­di­tions that are dis­tinct­ly ‘not aver­age.’ Under these unusu­al cir­cum­stances, nor­mal rules and automa­tion will prob­a­bly fail to pro­duce the fine, expres­sive pho­to­graph you have visu­al­ized.

–John P. Scha­ef­fer

Man­u­al expo­sure allows you to take con­trol of your image. It encour­ages you to halt and apply a slow­er, more con­sid­ered approach to your pho­tog­ra­phy, free­ing your mind from the shack­les of thought­less snap­ping at every oppor­tu­ni­ty. In a way, it fos­ters you to make cre­ative deci­sions with a pur­pose.

Mod­ern cam­eras pro­vide for mul­ti­ple ways to make the same expo­sure. Every day, many advanced and pro­fes­sion­al dig­i­tal pho­tog­ra­phers rely on the auto-expo­sure smarts of their cam­eras to achieve quick and effec­tive results. There are also sit­u­a­tions in which man­u­al­ly set­ting the expo­sure is the only viable tech­nique for acquir­ing the image you visu­al­ize. You’re encour­aged to exper­i­ment with and dis­cov­er the meth­ods that suit your pre­ferred style.

Ulti­mate­ly, man­u­al expo­sure isn’t nec­es­sary in most pho­to­graph­ic sit­u­a­tions. Nev­er­the­less, under­stand­ing how it works, and how to use it to achieve desired results, will undoubt­ed­ly be help­ful in cas­es that require it.

Sunny ƒ/16 rule of thumb

Every pho­tog­ra­ph­er should know the fol­low­ing rule of thumb: when your sub­ject is in direct sun­light, set your expo­sure to ƒ/16 and a shut­ter speed that match­es the rec­i­p­ro­cal of your ISO val­ue. For exam­ple, for a cam­era set to ISO 200, the cor­rect expo­sure for a sub­ject illu­mi­nat­ed by direct after­noon sun­light on a clear day will be ƒ/16 and 1/200 sec­ond. When the sit­u­a­tion calls for less depth of field and faster shut­ter speed, feel free to adjust the pro­por­tions accord­ing to the reci­procity law. An equal expo­sure at the same ISO speed will be obtained at ƒ/11 and 1/400 sec­ond, ƒ/8 and 1/800 sec­ond, and so forth.

Copy your auto-exposure values

In sit­u­a­tions beyond direct sun­light, one of the most nat­ur­al begin­ner tech­niques for exper­i­ment­ing with man­u­al expo­sures that pro­duce good results (most of the time) is by copy­ing the auto-expo­sure set­tings. This involves tak­ing sev­er­al tri­al images using your pre­ferred auto-expo­sure mode and ana­lyz­ing the expo­sure val­ues. If the results of a par­tic­u­lar pho­to­graph strike your fan­cy, switch your cam­era into man­u­al mode and repli­cate the shut­ter speed, aper­ture, and ISO.

Use a handheld incident-light meter

A more advanced tech­nique, yet one that’s incred­i­bly sim­ple and accu­rate (espe­cial­ly for por­traits or sub­jects with­in reach) is using an inci­dent-light meter (see Meter­ing Light). Con­tem­po­rary light meters take mea­sure­ments in either Aper­ture Pri­or­i­ty or Shut­ter Pri­or­i­ty modes. In either case, you set the ISO val­ue and either the shut­ter speed or aper­ture (depend­ing on the desired effect), and take a read­ing of the inci­dent light from the posi­tion of the sub­ject and with the lumi­sphere point­ing in the direc­tion of the cam­era. After tak­ing a mea­sure­ment, the light meter will dis­play the cor­rect expo­sure val­ues for the image—the two inputs pro­vid­ed by you, and the third one deter­mined by the meter based on a read­ing of the light.

For exam­ple, you want to take a por­trait in open shade on a bright sun­ny day. You have decid­ed that a nar­row depth of field will be your pri­or­i­ty because it pro­vides a pleas­ant sep­a­ra­tion between your sub­ject and the back­ground; hence, you choose ƒ/2. And, because there’s plen­ty of light, you decide on ISO 200. (The ISO val­ue may be adjust­ed if the meter spec­i­fies a shut­ter speed that you deem too slow.) With these inten­tions in mind, you input these val­ues into the light meter. To take an accu­rate read­ing of the light falling on your sub­ject, hold the light meter’s lumi­sphere direct­ly in front of your subject’s face and point it straight towards the camera’s intend­ed posi­tion. After mea­sur­ing the light (which takes a split sec­ond), the meter will dis­play the shut­ter speed nec­es­sary for achiev­ing a cor­rect­ly bal­anced expo­sure, which in this exam­ple is 1/1000 sec­ond. Adjust your camera’s shut­ter speed, aper­ture, and ISO to match the light meter’s expo­sure val­ues and take the pic­ture.

If you’re using an unusu­al­ly large and com­plex lens, the light meter’s rec­om­mend­ed expo­sure val­ues may require a slight adjust­ment of +1/3 to +1/2 EV to com­pen­sate for the dif­fer­ence in your lens’s trans­mis­sion val­ue (see F-stops and T-stops in Aper­ture). If you have an old­er light meter that doesn’t allow input of expo­sure com­pen­sa­tion, make the deter­mi­na­tion inde­pen­dent­ly when set­ting your camera’s expo­sure val­ues. For exam­ple, adding +1/3 EV to a shut­ter speed of 1/1000 sec­ond will pro­duce a shut­ter speed of 1/800 sec­ond, and adding +1/2 EV will result in 1/750 sec­ond. For­tu­nate­ly, new­er elec­tron­ic mod­els allow users to set expo­sure com­pen­sa­tion in the light meter, which is auto­mat­i­cal­ly fac­tored into the dis­played expo­sure val­ues fol­low­ing a read­ing.

Use the camera’s reflected-light meter

The most acces­si­ble and read­i­ly avail­able method for man­u­al­ly set­ting your camera’s expo­sure val­ues relies upon its built-in reflect­ed-light meter. With prac­tice, the process is incred­i­bly sim­ple and takes just sev­er­al sec­onds to com­plete; how­ev­er, it depends on the com­plex­i­ty of the sce­nario and how nim­ble you are at manip­u­lat­ing your camera’s expo­sure val­ues since the pro­ce­dure can dif­fer among dif­fer­ent mod­els. Before you begin:

  • Famil­iar­ize your­self with how and where your camera’s viewfind­er or LCD show expo­sure infor­ma­tion. (The con­ven­tion­al order from left to right is shut­ter speed, aper­ture, and ISO.)
  • Deter­mine which of the avail­able meter­ing modes at your dis­pos­al bests suits the sce­nario (because the tech­nique relies on their cor­rect use). Alter­na­tive­ly, and for the sake of sim­plic­i­ty, select either called eval­u­a­tive, matrix, or mul­ti (depend­ing on your camera’s brand).

Reit­er­at­ing two points from ear­li­er is essen­tial. First, the large notch (or zero) at the cen­tre of the light meter scale in your viewfind­er always des­ig­nates the stan­dard expo­sure index, which marks the point on the scale that your cam­era con­sid­ers opti­mal expo­sure. In this case, “opti­mal” is high­ly depen­dant on your meter­ing mode. For instance, when your cam­era is set to eval­u­a­tive meter­ing, opti­mal is deter­mined by the camera’s auto-expo­sure pro­gram based on a sophis­ti­cat­ed analy­sis of the scene; in spot meter­ing mode, opti­mal is the expo­sure val­ue that will ren­der the tone that over­laps with the spot as mid­dle grey in the result­ing image. Sec­ond, in Man­u­al mode, the expo­sure lev­el indi­ca­tor shows how much your set expo­sure val­ues devi­ate from the stan­dard expo­sure index (i.e., the camera’s opti­mal). When the expo­sure lev­el indi­ca­tor is posi­tioned direct­ly below the stan­dard expo­sure index, there’s no devi­a­tion from opti­mal expo­sure.

Last­ly, it’s nec­es­sary to rec­og­nize that the expo­sure lev­el indi­ca­tor is dynam­ic and liable to wild fluctuations—shifting between indi­ca­tions of too much or too lit­tle exposure—depending on the part of the scene your cam­era is aimed. This behav­iour is espe­cial­ly true when rely­ing on spot meter­ing mode to take your expo­sure read­ings.

The process of set­ting your expo­sure val­ues man­u­al­ly using the on-cam­era expo­sure meter is straight­for­ward whether you’re using a cam­era with an opti­cal or elec­tron­ic viewfind­er, live view LCD, or rangefind­er. In the inter­est of more pre­cise instruc­tions, the remain­der of this guide will assume your cam­era uses an opti­cal viewfind­er, as is stan­dard with every DSLR. Rest assured that the process is sim­i­lar across most cam­eras.

After com­pos­ing your image in the viewfind­er, take a look at the expo­sure meter and pay close atten­tion to where the expo­sure lev­el indi­ca­tor is com­pared to the stan­dard expo­sure index. (For the pur­pose of this exer­cise, assume the stan­dard expo­sure index always marks an objec­tive­ly “cor­rect” expo­sure.) Since every cam­era will main­tain its man­u­al expo­sure val­ues between pow­er­ing on and off, it’s unlike­ly that your set­tings will be cor­rect for the sub­ject at hand, espe­cial­ly if your last pho­to was tak­en at a dif­fer­ent time of day or under dif­fer­ent ambi­ent light. If the indi­ca­tor is on the pos­i­tive side of the index, the camera’s meter is advis­ing you that your cur­rent expo­sure val­ues will pro­duce over-expo­sure in the pho­to. If the indi­ca­tor is on the neg­a­tive side of the index, the camera’s meter is advis­ing you that your cur­rent expo­sure val­ues will pro­duce under-expo­sure. If your camera’s expo­sure val­ues fall out­side the lim­its of the light meter’s dis­play, either the indi­ca­tor will flash, or tri­an­gu­lar arrows will appear at the end of the scale cor­re­spond­ing to over- or under-expo­sure. In either of these three cas­es, adjust your expo­sure val­ues (shut­ter speed and aper­ture) or ISO in a man­ner that brings the indi­ca­tor nee­dle to align with the index mark. “Cor­rect” expo­sure is achieved when the indi­ca­tor aligns with the index.

For exam­ple, if your cam­era is cur­rent­ly set to 1/80 sec­ond, ƒ/1.4, and ISO 1600, and the expo­sure lev­el indi­ca­tor is at +2 EV, the cam­era believes that your cur­rent expo­sure val­ues and ISO will pro­duce a pho­to that is over-exposed by two stops. To rem­e­dy this, adjust one of the three para­me­ters by –2 EV. Alter­na­tive­ly, you may change two of the three set­tings by –1 EV, or all three by –2/3 EV. Regard­less of how you reach a total com­pen­sa­tion of –2 EV doesn’t mat­ter (see Reci­procity Law). In this par­tic­u­lar exam­ple, if your shut­ter speed and aper­ture suit your sub­ject, then reduce the ISO by –2 EV to ISO 400 for low­er image noise.

Of course, indis­crim­i­nate­ly fol­low­ing the advice of the light meter in man­u­al mode is no dif­fer­ent than rely­ing on it entire­ly in one of the auto-expo­sure modes. You should always use your bet­ter judge­ment as a pho­tog­ra­ph­er to under­stand the sub­ject, the scene, and where the camera’s pro­gram may go astray. For exam­ple, if you’re tak­ing a pic­ture of a per­son dressed in very bright cloth­ing against a bright back­ground, adjust­ing your expo­sure val­ues and ISO to align the indi­ca­tor with the stan­dard expo­sure index will pro­duce an image whose tones are mid­dle grey and not rep­re­sen­ta­tive of the sub­ject. As with expo­sure com­pen­sa­tion, it’s often nec­es­sary to use your bet­ter judge­ment and stray from what the cam­era con­sid­ers opti­mal expo­sure. In this exam­ple, a cor­rect expo­sure would be achieved when your expo­sure val­ues and ISO shift the expo­sure lev­el indi­ca­tor to show +1 EV to +1½ EV. Con­verse­ly, when tak­ing a pho­to of a dark­ly dressed sub­ject against a back­ground of low-reflectance foliage, you’ll achieve a cor­rect expo­sure when your expo­sure val­ues and ISO place the expo­sure lev­el indi­ca­tor to –1/2 EV to –1 EV.

With ade­quate prac­tice and fre­quent rep­e­ti­tion, the oper­a­tion of your camera’s expo­sure con­trols will become instinc­tive and guid­ed by mus­cle mem­o­ry. Get out there and prac­tice.