# EX­PLAINED

## We strip through the jar­gon to break down colour tem­per­a­ture — what it is, what to look out for, and how to en­sure you’ve got it right, ev­ery time

New Zealand D-Photo - - CONTENTS -

The D-Photo team talks through colour tem­per­a­ture — and how to en­sure you’ve got it right, ev­ery time

The tech­ni­cal def­i­ni­tion of colour tem­per­a­ture is full of terms such as the ‘Planck­ian curve’, or ‘chro­matic­ity space’ — in short, it’s very confusing, a wee bit stale, and leaves most feel­ing even more baf­fled than be­fore. It’s for this rea­son that many pho­tog­ra­phers stick to Auto White Bal­ance, even when they might oth­er­wise work ex­clu­sively in man­ual modes.

In lay­man’s terms, colour tem­per­a­ture de­scribes the way in which dif­fer­ent light sources pro­duce dif­fer­ent-coloured light, due to the var­i­ous pro­por­tions of the three pri­mary colours — red, green, and blue — that form white light. A can­dle em­anates a warm, orange glow, for ex­am­ple, while the rays of the mid­day sun on a clear day emit a bluish tint.

When the colour tem­per­a­ture is high, more blue light ex­ists, and when the colour tem­per­a­ture is low, there’s more red. Th­ese dif­fer­ent colours can be ex­pressed us­ing a num­ber, mea­sured in Kelvins — a term that you prob­a­bly came across back in your high school sci­ence class, but have prob­a­bly long for­got­ten. The scale is an ex­ten­sion of the Cel­sius scale, based on the colour of the light, and was con­ceived by de­ter­min­ing the colour of a black-body ra­di­a­tor as it heated to vary­ing tem­per­a­tures. At lower tem­per­a­tures, the chunk of metal glows red, then orange, then yel­low. As it gets hot­ter, the metal turns white, and at its hottest, it em­anates blue. This change in colour is what we use as a ba­sis for the colour tem­per­a­ture of light in photography.

So, why does any of it mat­ter? Well, while the hu­man eye ad­justs con­tin­u­ally to chang­ing light con­di­tions, dig­i­tal cam­eras are sim­ply not as good at adapt­ing chro­mat­i­cally, nor are their sen­sors quite so le­nient. In­stead, cam­eras han­dle colours by iden­ti­fy­ing the colour cast, then adding the same amount of the op­po­site colour to try and cre­ate a neu­tral image, where whites look as white

as pos­si­ble. This is your white bal­ance set­ting, and if you are record­ing any for­mat other than RAW, this set­ting per­ma­nently de­ter­mines the colour bal­ance of your recorded image. Though Auto White Bal­ance yields great re­sults in day­light sit­u­a­tions, it doesn’t do quite so well in low light, or mixed light­ing (where it tends to pro­duce an av­er­age). As a re­sult, im­ages are some­times un­wit­tingly drenched in a colour cast — that is, an over­all blue or orange tint.

So, if you’re tired of find­ing that your im­ages are veiled in an un­nat­u­ral hue, if you want con­sis­tency in colour across your im­ages so that it’s eas­ier to make batch ed­its or sync through its set­tings or dial in your Kelvin tem­per­a­ture, and ex­per­i­ment with how white bal­ance af­fects im­ages in real time via the cam­era’s back LCD screen. The medium-for­mat mir­ror­less Fu­ji­film GFX 50S boasts a 3.2-inch 2.36m-dot touch­screen LCD that’s also avail­able for image play­back, menu nav­i­ga­tion, and live view shoot­ing. This LCD fea­tures a unique tilt­ing de­sign which moves both 45 de­grees down­ward and 90 de­grees up­ward for shoot­ing from high and low an­gles, and it tilts 60 de­grees to the side to ben­e­fit shoot­ing in the ver­ti­cal ori­en­ta­tion when in live view. Plus, with sev­eral ded­i­cated di­als for ad­just­ing ex­po­sure set­tings, and a top LCD screen that set­tings across the board, or if you want to shoot true, ac­cu­rate colour — here’s where man­ual white bal­ance comes in.

The Kelvin tem­per­a­ture scale for photography most com­monly ranges from around 1700K to 9000K, so keep­ing some key val­ues in mind will also go a long way. In short, in­can­des­cent light is 3200K, white flu­o­res­cent light is 4200K, sun­light is 5500K, day­light with cloud cover is 6000K, and shade is 7000K.

The quick­est way to get your head around man­ual white bal­ance is to turn your cam­era’s live view mode on, click dis­plays white bal­ance and ex­po­sure data, the GFX 50S makes man­ual easy.

Fur­ther en­sur­ing that noth­ing comes in the way of ex­act image ren­di­tion, the heart of the GFX cam­era sys­tem boasts a 43.8 x 32.9mm 51.4-megapixel CMOS sen­sor, which pairs with the X-Pro­ces­sor Pro image pro­ces­sor to pro­duce an ex­tremely wide dy­namic range and high res­o­lu­tion, as well as an ex­tended sen­si­tiv­ity range of ISO 50, right through to a mas­sive 102,400.

To find out more about the imag­ing ca­pa­bil­i­ties of the Fu­ji­film GFX 50S, head to fu­ji­film.co.nz.

2500K

4500K

7500K

9000K

FI­NAL IMAGE 5500K, ADAM CROY

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