studio lighting
Working with studio lights Common rules Common rules of physics apply to the use of artificial light sources. When sunlight passes through greater amounts of particles in the atmosphere at dawn or sunset, exposure times increase compared to a reading taken at noon. This applies to clear and overcast days. Exposure times will obviously be shorter on a clear day. Applying these rules to a studio situation, the greater the impedance to the light (diffusion, reflection, filtration) the longer the exposure. In direct light (no diffusion, reflection, filtration) the shorter the exposure. Another simple rule. The amount of light falling on a subject decreases to 1/4 of its original intensity when the light to subject distance is doubled, and increases by 4x when the light to subject distance is halved. For example, if a reading of f16 is obtained when the light to subject distance is one metre, at two metres the reading would be f8, at four metres f4. These rules do not change regardless of the light source. It is also important to remember contrast in a studio situation is created not only by the reflectance level of the subject matter (SBR) but also by lighting ratios. When referring to lighting ratios the photographer is also referring to lighting contrast. See ‘Contrast and Compensation’.
Key light one metre from subject
Key light two metres from subject - Fabio Sarraff
Activity 3 In a darkened studio place a light one metre from the studio wall and take an incident reading, with the light on, of the light falling upon the wall. Note the reading and move the light on the same axis another one metre away from the wall. Note the reading. Double the distance once more, making a total of four metres. The final reading will be four stops less than the first. What will the distance of the light from the wall have to be to achieve a meter reading of three stops less than the first?
153
