Winston C Hall Tuner Photography

Size: px

Start display at page:

Download "Winston C Hall Tuner Photography"

Hilary Perry
7 years ago
Views:

1 Scene Contrast and Determining Lighting Ratios Methods for Determining Lighting Ratios Tutorial Created By: Winston C Hall Tuner Photography 315

2 What is Contrast? Contrast in photography is the difference in the brightness between the highlights (brightest) and shadows (darkest) in a scene. The contrast of a scene is either expressed as a ratio or as the number of stops between the highlights and shadows based on two meter readings. Two factors that influence the amount of contrast in a scene: The amount of light that is being reflecting off the subjects/objects in the scene. The intensity of the light striking the objects. Scene contrast depends on the amount of light that is being reflected by the objects in a scene. Very few objects reflect more than 80% of the light that is striking it and very few items reflect less than 4.5% of the light that is striking it Tonal Values If a scene has exactly the same amount of light falling on every object in the scene and every object is reflecting the same amount of light there would be no shadows or highlights and the scene would be very low contrast. The histogram would look like the one below. Measuring Lighting Ratios Tonal Values In flash photography the lighting ratio is the difference in brightness between the key and fill lights. This difference is expressed as a ratio. In a sunlit scene the ambient light from the sun would be the key light and the fill light is the light that is illuminating the shadow areas in the scene. To achieve a desired lighting ratio with a flash the key and fill lights are assigned different power settings. The goal with this type of set up is to control the light falling in the different regions in the scene. Be to control the lighting ratio in a scene is the essential part of studio lighting or outdoor portrait photography. 2

3 Methods for determining a lighting ratio Outlined in this tutorial are three different methods for measuring the main and fill light. The most accurate way to determine the lighting ratio is to use a hand- held light meter. Determining the lighting ratio with a light meter is very different from using the light meter to determine a proper exposure reading. To determine the proper exposure reading, place the meter at the subjects location and pointed the dome back towards the camera and record the meter reading. The purpose of this type of reading is to achieve a neutral tonal value, not to determine the difference in contrast. The descriptions listed here are used for purpose of determining the lighting ratio. Method #1: Reflected Light Meter The ideal metering mode for this method is to use a spot meter. The area being illuminated by the key light and the area being illuminated by the fill light need to have the same amount of reflectance. This method is most commonly used when determining the contrast on the subjects face for a portrait. Stand at the same angle as the camera to subject. Place the spot meter on the side of the face that is being illuminated by the key light or sun outdoors and record the reading. Take the second meter reading from the shaded (shadow) portion of the subjects face. Method #2: Light Meter and a 18% Gray Card First step is to record a meter reading of the key and fill lights by holding the 18% gray card at an angle between the key light and the subject. Measure the light reflecting off the card. The angle of the card needs to be the same angle that the camera will see the subject. The second step is to measure only the fill light. Place the 18% gray card at the subject and pointing towards the camera, shade the surface of the card from the key light, record the reflected light meter reading. Method #3: Using an Incident Meter with Flash Use a hand- held light meter to take a incident meter reading by extending the dome on the to the extended position, place the meter at the subject with the dome pointing at the key light. Fire both the key and fill light to record the reading. The second meter reading should measure only the fill light. Place the meter at the subject with the dome pointing towards the camera and shade the dome from the key light. Fire both the key and fill light to record the reading. 3

4 Determining the ratio The result of using method 1, 2 or 3 is that you ll end up with two different meter readings. The two readings need to be changed into a lighting ratio. First Step: Determine the difference between the two different meter readings. Example: if the key plus fill meter reading is f/16 at 1/160 sec and the fill meter reading was f/8 at 1/160 sec the difference in stops is: F/8 to f/11 is one stop (1.0), F/11 to f/16 is another stop (1.0) Difference between f/8 to f/16 would be two stops (2.0) Second Step: Is to change the number of stops into a lighting ratio. The ratio tells us how many times brighter the quantity of the key plus fill light is to the fill light. Every stop in difference represents twice the brightness of the light. One stop difference = 2:1 ratio Two stop difference = 4:1 ratio Three stop difference = 8:1 ratio Four stop difference = 16:1ratio Ratios at 0.3, 0.7, 1.0 of a stop 0.0 Stop difference = 1:1 ratio 0.3 stop difference =1.25:1 0.7 stop difference = 1.5:1 1.0 stop difference = 2:1 ratio 1.3 stop difference = 2.5:1 1.7 stop difference = 3:1 2.0 stop difference = 4:1 ratio 2.3 stop difference = 5:1 2.7 stop difference = 6:1 3.0 stop difference = 8:1 ratio 3.3 stop difference = 10:1 3.7 stop difference = 13:1 4.0 stop difference = 16:1 4.3 stop difference = 20:1 4.7 stop difference = 26:1 5.0 stop difference = 32:1 4

5 Using Lighting Ratios If you d like to set up a 4:1 ration for a portrait. You ll need to adjust the flash power compensation until you can achieve a two- stop difference between the key and fill light. If the lighting ratio you desire is a multiple of two such as a 4:1 or 8:1 it is fairly easy to quickly determine the difference in stops to achieve the ratio Stop Difference Ratio Lighting Description Stop difference 1:1 ratio Flat lighting. 0.3 stop difference 1.25:1 High Key 0.7 stop difference 1.5:1 1.0 stop difference 2:1 ratio General color photography. Medium key. 1.3 stop difference 2.5:1 1.7 stop difference 3:1 General black and white photography 2.0 stop difference 4:1 ratio Common portrait lighting. 2.3 stop difference 5:1 2.7 stop difference 6:1 3.0 stop difference 8:1 ratio Dramatic portrait lighting. Low key 3.3 stop difference 10:1 3.7 stop difference 13:1 4.0 stop difference 16:1 ratio Very dramatic lighting. 4.3 stop difference 20:1 4.7 stop difference 26:1 5.0 stop difference 32:1 ratio Extreme dramatic lighting. 5

BASIC EXPOSURE APERTURES, SHUTTER SPEEDS AND PHOTO TERMINOLOGY

BASIC EXPOSURE APERTURES, SHUTTER SPEEDS AND PHOTO TERMINOLOGY EXPOSURE Exposure is the response of a photographic emulsion to light. The emulsion is made of a material (silver) that is sensitive to light.