استخدام مصدرين للضوء .. معدات وتقنيات إضافية .. المرشد خطوة بخطوة للتصوير الفوتوغرافي

استخدام مصدرين للضوء .. معدات وتقنيات إضافية .. المرشد خطوة بخطوة للتصوير الفوتوغرافي

Using two light sources

There are times when one lamp is not enough , and you must add another light from a different direction . This may be to reveal detail in shadow areas , light one part of the picture separately , or simply to illumi- nate a larger area . The most important rule in lighting is to decide exactly what job you want each lamp to do . Never add lamps indiscriminately just to increase the light .

Always treat one lamp as your main source , and begin by selecting its best posi- tion . If it is close in , it will create strong contrast . Further back it will have a more even effect across the subject .

Filling - in shadows

Often your main lamp will reveal form and shape in the subject but create dark , empty shadows . You can fill these by placing a second lamp opposite the first . If the two lamps are the same distance from the sub- ject they will " cancel out " and give un- natural double shadows . To avoid this , " bounce " ( reflect ) the second light off white card , or diffuse it . This dims and softens the light , so that only one set of strong shadows are formed by the main lamp . You can fill - in shadows , even when working with a single lamp , by reflecting some of the light back on to the subject , as shown right .

Lighting the background

You can control the tones in the subject and the background independently of each other by using a second lamp to light the back- ground . A gray card background , placed a reasonable distance behind the subject , helps you to assess the effect of the second lamp . If the card is lit more strongly than the subject , it will appear almost white . But if the subject is lit more strongly , and the exposure adjusted accordingly , the back- ground will then appear quite dark .

Using one lamp and a reflector

The picture , left , was lit by a small floodlight about four feet ( 1.2 m ) from the figure . The strong side lighting shows the form of the figure and brings out the texture of the wall , but the shadow areas are unnaturally harsh and lack detail . These dark shadows could be reduced by using a second , weaker light source to fill - in . For the picture , below left , a large white reflector board was used to reflect back diffused light . The shadow areas were illuminated without creating conflicting shadows . The effect is less arti- ficial than the first picture and more like sunlight plus light from the sky . Notice how the lighting is still rather uneven left - to - right across the picture this could be corrected by increasing the distance of the lamp , or by printing - in ( see p . 86 ) when printing .

Controlling background lighting

Using two lamps on a subject enables you to control the lighting of your subject very accurately . For the still - life , left , two lamps and a roll of seamless paper for the background were used . The lamp on the left provided the main illumination . The one on the right lit the background independently , so that it was possible to control the background tone relative to the subject . In this way you can arrange that the lightest parts of the subject appear against the darkest part of the background and vice versa .

Eliminating shadows
The still - life above was lit by a diffused lamp above the camera . There are no hard shadows , but light tones tend to merge with the bright background .

Varying lighting distance
When you are photographing strong three dimensional shapes . using a second light source at varying distances gives complete control of tonal values . In the example shown right , the top pic- ture was lit with two equally placed floodlamps , resulting in even tone and flatness of form . For the lower picture , the distance of the right hand lamp was doubled , quartering the illumination from this side . This has darkened two faces of the cube and rounded the cone and cylinder . Placing the second lamp even further away would increase the effect .

Inverse square law
Doubling the distance between a lamp and a subject quarters the surface illumination . This " inverse square law " strictly applies only to compact , bare lamps Reflectors upset the relationship slightly . But it forms a good working guide for position- ing lights . You will meet the law again when you use extension bellows ( see p . 103 ) or calculate exposure for flash ( see p . 112 ) .

Using two lamps , bounced
For the picture above two lamps were used , both directed on to the ceiling . The result is even . soft , top lighting , similar to the quality given by a diffused domestic ceiling lamp at night . ( Flash bounced off the ceiling gives very similar results . see p . 113. ) This lighting can form dark . downward shadows . To reduce this effect you should illuminate the ceiling above the camera more than the area directly above your subject .

Using a spotlight and floodlamp
The picture below was lit by one spotlight , high and to the right of the camera , plus a photoflood from the rear left . The lighting is hard but naturalistic - you have the impression that the man is using a reading lamp in the room with other lighting . Notice how the photoflood lights the side of the head which would otherwise merge in shadow with the chair .