Mas­ter com­plex ex­po­sure cal­cu­la­tions to en­sure ac­cu­rate and re­li­able cap­ture of high­light and shadow de­tail

Digital Photograper - - Contents -

A guide to en­sur­ing ac­cu­rate cap­ture of high­light and shadow de­tail

Many dig­i­tal cam­eras are now ca­pa­ble of cap­tur­ing de­tail across a bright­ness range of up to 15EV, gen­er­at­ing data in the light­est and dark­est parts of a scene. How­ever, ul­tra-high con­trast, such as that found in mid­day light­ing, can still pose a ma­jor chal­lenge, where the light in­ten­sity falls out­side of the cam­era’s na­tive dy­namic range. In these cir­cum­stances, Eval­u­a­tive me­ter­ing will most likely be un­able to re­li­ably sug­gest an ideal ex­po­sure to balance all tones. Spot me­ter­ing will help with per­fect­ing ei­ther shad­ows or high­lights, but will be unsuitable in wider-framed com­po­si­tions. Gen­er­ally, in these con­di­tions, it is bet­ter to use mul­ti­ple me­ter­ing op­tions, to gain an es­ti­mated range of pos­si­ble set­tings and then tailor these man­u­ally.

While this style of work­ing is slower than re­ly­ing on au­to­matic ex­po­sure con­trol alone, tak­ing the time to mon­i­tor shad­ows, mid­tones and high­lights in­di­vid­u­ally will en­sure you gen­er­ate a file with re­cov­er­able in­for­ma­tion at each end of the tonal scale. This method al­lows for max­i­mum de­tail in a sin­gle frame, with­out merg­ing mul­ti­ple brack­eted images in soft­ware. Of­ten you will find that the photo ap­pears too bright or too dark in-cam­era, but by com­bin­ing these steps with the pop­u­lar ‘ex­pos­ing to the right’ tech­nique, you can out­put a more us­able file for later pro­cess­ing.

1 GEN­ERAL ME­TER­ING Be­gin by us­ing Eval­u­a­tive (or Ma­trix) me­ter­ing to gain a rough in­di­ca­tion of the type of set­tings that will be nec­es­sary. Take a read­ing from an ‘av­er­age’ area of the scene and note the sug­gested set­tings.

2 TIGHTER ME­TER­ING Switch to Cen­treWeighted or Spot me­ter­ing and take read­ings from high­light, midtone and shadow ar­eas in turn. Com­pare these val­ues with the ini­tial ones to iden­tify ‘prob­lem’ ar­eas to mon­i­tor closely.

3 SWITCH TO MAN­UAL Move to man­ual mode on your cam­era’s mode dial and en­ter set­tings close to that of the ‘best’ frame from the pre­vi­ous step. Man­ual will en­sure the cam­era doesn’t change ex­po­sure as you re­com­pose your shot.

4 OB­SERVE THE HIS­TOGRAM Use live his­tograms when util­is­ing Live View mode, or display an over­lay dur­ing re­view, to check that no tones touch the sides of the graph. Also note whether the dis­tri­bu­tion of tones is as even as pos­si­ble.

5 USE HIGH­LIGHT/SHADOW WARN­INGS These are good for quickly in­di­cat­ing whether there are any large ar­eas of miss­ing high­light or shadow de­tail. While his­tograms are more pre­cise, vis­ual warn­ings rapidly show gen­eral ex­po­sure ac­cu­racy.

6 PUSH THE EX­PO­SURE Once the ex­po­sure is ‘cen­tred’, with good de­tail guar­an­teed, in­crease the ex­po­sure in order to move more tones to the right of the his­togram, for op­ti­mal colour and qual­ity. Work in 1/3-stop in­cre­ments for pre­ci­sion.

AF­TERGREATER CON­TROL By mea­sur­ing high­lights, shad­ows and mid­tones separately, then us­ing man­ual, the ideal ex­po­sure can be locked in, free from un­ex­pected changes by the me­ter­ing sys­tem

BE­FORE Inset BLEACHED HIGH­LIGHTS Eval­u­a­tive me­ter­ing is con­fused by the large shadow ar­eas, re­sult­ing in over-com­pen­sa­tion in the high­lights,which are void of re­triev­able de­tail

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