PHOTOGRAPHY- 14

 PHOTOGRAPHY- 14

Light source

Quite relevant it is to forewarn beginners of the impending damage to picture quality from indiscriminate use or choice of light. This caution tries to ‘restrict’ use of any light, especially for colour photos ; light sources ought to be understood for their energy expressed in Kelvin units or Kelvin degrees. Kelvin values above 5600 are closer to daylight in their spectral component and values below 4500 tend to throw more reddish wavelengths that show off as colour tint not easy to visually accept. All my observations in this regard pertain to Film and honestly I have no idea as to how the situation is handled by Digital scheme of Photography.

Kelvin ratings at or around 6000 are more towards the blue end of the spoectrum- meaning that It simulates mid- day Sunlight; so colour values received by camera nearly match our perception of tints in day light by human brain. On the contrary, values of Kelvin at or below 4000 are unbearably reddish in spectral component and quite some compensation by filtration is essential[use of strong blue filteris advised[. Why use undesirable light and attempt correction?

It was a learned borrowing[ using of balancing filters] from cinematographers  who may have to shuttle between out door and indoor sequences on the same film stock.Even then the most astute among Cinematographers finish indoor needs before moving to out door and vice-versa with due change of appropriate film in place.

Well established Cinematographers could command the right film for use or could abstain from further work on that project citing the ground that “my name/our names is/are at stake[s]and cannot afford to lose label of expertise by compromising on filmstock”. They were well within the domain of fairplay because , any use of improper match like light on studios and film characteristic like response to spectral behaviour of light is bound to destroy image quality. So, friends , let us recognize that film manufacturers used market films T [BALANCED FOR TUNGSTEN inside studios =LOW KELVIN ] and D[BALANCED FOR DAYLIGHT OR HIGHER KELVIN typical of outdoor midnoon light ]. Wrong film in improper light conditions would bring off bizarre colours , bluish shadows , reddish brown hair colour and so on. Any movie-goer would rightaway fix it on the Cinematographer[s] though it was the moviemaker who failed to provide the right kind of film for work [or as in some strange situations the cinematographer hesitated to ask for right film , fearing the prospect of losing the assignment].In such situations balancing filters cannot ensure complete justice to colour rendition. For technical perfection ‘some light is no light ‘ is the watchword.The higher degree of success in colour rendition among later Indian movies was in large measure due to trained technicians brought out through Film Technology institutions  that fed them with sound foundations on LIGHT-FILM- PROCESS relationship + Typical characteristics of FILM BRANDS + THE CODES on them signifying their adaptability to situations. Thus, the industry could bring off movies at par with West in cinematography though widely constrained by ‘not-too –upto-date movie Cameras’.

STILL CAMERAS  Vs LIGHT BALANCING

Still photography too requires a set of lIghting gadgets like lamps kept in right orientation to privide general lighting as in photo studios, in addition to 1 or more lights –Key and Fill-in. These were good enough to help Black and White portraiture. With the advent of colour as the lone medium of image recording , these lights turned irrelevant by their Kelvin values [low end].

Special high Kelvin lamps are installed to handle light requirements for coour work. Curiously all through the history of Amateur photography, light quality in terms of Kelvin has always been a comfort zone in that Flash lights for Cameras throw up light valued at 5500-6000 K^o providing a blue-rich beam of light to safeguard colour characteristics of images as well as spectral requirements of Amateur colur films[unless specified otherwise by film manufacturer.] However in using Flash light overcertain distance can prove to be a menacem especially with lenses Tele/ Zoom. Both are capable of drawing the image closer from objects at a distance. I.E., THE IMAGE LOOKS LARGER ,THOUGH OBJECTS ARE PHYSICALLY AWAY . It means that the beam of light intended to light up image details may turn weak before reaching the object [due to distance] This is ecause , light /intensityof it is governed by”Inverse Square Law”

Inversw square Iaw prescribes that

The physical quantum of light  received on a surface is inverely proportional to the square f the distance.

Consider 2 objects at 2 places [distance X] and [distance 2X]

While object at X receives light of some intensity, that at 2X receives only ¼ of what is received at X, due to ‘fall off’ effect. So, while using special optics designed to magnify image, care to send in extralight is a logical need.

To continue

K.Raman