1/20 sec; f/5.6; ISO 400; manual Mode; Partial Metering, 88mm; Flash did not fire

Photo Editing

Aperture | Shutterspeed | ISO | Exposure Triangle | Metering | Exposure Compensation | Flash | Reflectors

Light is the source of energy for the universe and is the central image of many religions and the photographer's top resource. The word "photography" derives from the Greek and means, literally, “light writing.” From the power of full sun over water to the beam from a single candle, it is light photographers play with, light in its many moods and manifestations that we capture on film.

Sunlight (Ambient Light)

As a light source, the sun is the primary source of infrared light. It emits visible light, infrared light and ultraviolet light. However, daylight can be unpredictable due to changing weather conditions and clouds tend to block most of the infrared spectrum. The best infrared photographs therefore tend to be captured in direct sunlight.

Back Lighting

- Know that when using a back-lit source, it doesn't have to technically be light. For example, when taking a picture of a subject in front of a bright sky, this will produce a back-lit situation even if the sun is not visible as a light source.
- There are two critical aspects when working with the back-lit situations. The Metering Mode on your camera determines the lighting conditions, and your digital camera's "brain" then determines the best shutter speed and aperture that should be used to create the type of picture you want. Unfortunately, there is a serious but subtle flaw with this approach.The camera cannot read your mind, and therefore doesn't know what type of picture you want. Most of the time, this is not a problem. However, in the world of photography lighting, back-lit situations are often tricky because there are several effects you can create from any given situation and the camera does not know what you want for certain.
- What you want to do in capturing a silhouette, is to use matrix metering, because this approach takes into account all available light and averages the result to set your camera's aperture and shutter speed.
- When taking a picture of a bright background having one dimly lit subject in the foreground, the camera will think your "subject" is a lot brighter than it is. That is because your camera will think your subject is everything in the viewfinder, not just the subject in the foreground. This will underexpose your subject and turn them into a silhouette.
- To avoid this result, you will need to use fill flash. A fill-flash will “fill” your subject with the required light, resulting in a properly lit subject as well as a bright background.

Side Lighting
- Depending on the angle of the light source, part of your subject will be in light and part shadows.
- To produce a dramatic effect on your photos, use photography lighting from the side.
- In order to achieve this type of dramatic impact, pose your subject in front of a window, with one of their shoulders facing the camera.
- You can rotate the subject relative to the window, in order to achieve different intensities of light and shadow on their face.
- Your camera will expose properly for the bright side and will cast the other side in shadows. If you do not want this type of effect, there are two things you can do. One is to use fill flash.
The other is to use natural lighting without a flash to produce an overall softened effect.
Using something like a white reflective surface (poster board, for example) will reflect light onto the darkened side of the face and produce an added depth to your photographs.

Artificial Lighting

In the absence of adequate sunlight, photographers use artificial light to illuminate scenes, both indoors and outdoors. The most commonly used sources of artificial illumination are the electronic strobe, or “flash“; tungsten lamps called photofloods; and quartz lamps.

Tungsten light (Light Bulb)

Normal tungsten bulbs emit more infrared radiation than visible light; a 100W tungsten bulb emits only 1W of visible light, but 99W of infrared. Unfortunately most of the infrared light is deep IR and falls outside of the sensitivity of digital camera sensors. You would need higher ISO setting and longer exposure to capture infrared photographs under tungsten illumination.

Fluorescent light (Tubes)

Fluorescent light bulbs are designed to save energy and reduce heat by only emitting visible light. There is still just a bit of near IR that is emitted but this is so low of an intensity that infrared photography under fluorescent lighting is impractical.

Diffused lighting

Diffused lighting is modified light source to prevent an over-exposed, harshly lit photograph.
- Sometimes, the best thing to know about lighting is when to NOT TAKE A PICTURE because the available light is just going to be too harsh.
- That is when you want to soften the incoming light and reduce some of the contrast for a more pleasing photograph.
- Be aware that there are certain times of the day which are good (as well as bad) for taking pictures.
- The best time of day to take pictures is when it is slightly overcast, or when the sun goes behind a cloud.
- The same effect can also be created when your subject is in the shade. In that case, the light will be much more natural and will result in a better photo.
- The worst time of day to take outdoor pictures is at high noon because generally that is when the sun produces the brightest light.
- Most beginning photographers think that shooting photographs when the sun is overhead, is an ideal time because of the availability of so much light.
- Unfortunately, colors will be washed out and the shadows are too dark. (This is the direct opposite of the photography myth that the best photography lighting occurs in bright sunlight.)
- The other is to use natural lighting without a flash to produce an overall softened effect.
- Using something like a white reflective surface (poster board, for example) will reflect light onto the darkened side of the face and produce an added depth to your photographs.

HID light

HID (high intensity discharge) lamps produce light by surging electricity through pressurized gas. Normally, these lights are used in locations such as shopping malls, sports stadiums and street lighting. Like fluorescent light, HID is a discontinuous light source, meaning that it doesn’t burn (continuous light sources are the opposite – the sun, candles etc. all burn). In common with other discontinuous light sources, HID emits mainly visible light and quite a bit of far infrared light but just like fluorescent lights lacks useful output in the near IR range that is used for infrared photography.

Electronic flash light

Electronic flash units emit quite a bit of near IR light and other than the sun is the most useful light source for IR photography. In fact, flash units emit just as much and in some cases even more infrared light than visible.

Strobes

The electronic strobe (see Stroboscope) consists of a glass quartz tube filled with an inert gas--a halogen--at extremely low pressure. When high voltage is applied to the electrodes sealed at the ends of the tube, the gas ionizes and produces an intense burst of light of very short duration, a flash. Although large, special-purpose units can produce a flash of about 1/100,000 of a second, most produce flashes lasting from 1/5000 to 1/1000 of a second.

Strobe units must be synchronized with the shutter of the camera so that the burst of light covers the entire scene. Synchronization is achieved through an electrical connection between camera and flash unit, either a bracket mounted on top of the camera, called a hot shoe, or a cord called a synch cord that runs from the camera's synchronization socket to the strobe.

Automatic strobe units are equipped with sensors, photocells that automatically adjust the duration of the flash for a particular scene. The sensor, which measures the intensity of the flash as it occurs, cuts off the light when adequate illumination is obtained.

The dedicated strobe, a newer type of automatic strobe, is designed to function as a unit with a particular camera. The electronic circuitry of the flash and camera are integrated. The sensor is located inside the camera and gauges the amount of light at the film plane, allowing more accurate measurement of flash intensity.

Strobe units vary in size from small camera-mounted units to large studio units. Generally speaking, the larger the unit, the greater the intensity of light produced. Camera-mounted strobes are adequate for illuminating small scenes, but to illuminate a large scene evenly, and with a single burst of light, a powerful studio unit is needed.

EXPOSURE Ms. GREGSON


© Capture Design & Photography, 2014