Sunday, May 16, 2010

Multiple Lights

Multi Light Usage

Using more than one light for studio work involves placing the lights in relationship not only to the subject, but to each other as well. The relationship of lights not only depends on the physical placement, but also the power output, modifiers used, temperature of light, and more interactions than could be covered in several books. For the purpose of this class, we will be working with lights of the same temperature and dealing primarily with power, placement and modifiers.

How Does Light Work

The main thing to remember when using multiple lights (single light as well) is how light works. Light can only travel in a straight line. It does not bend. Light can be redirected easily though. Light can be filtered for a specific color; once this is done it cannot be undone. Light is made up of countless individual rays of light that cannot be seen individually by us, only as a whole. Light is not a big solid beam, but can be made to look that way.
The difference between direct light and diffused light is not a softening of the light; light cannot be softened, only redirected. What we call soft or diffused light is actually light that has been scattered. The light is still traveling in a straight line, but there are now countless rays being directed in every angle imaginable instead of in a more direct path. This randomness of light paths is what fills in areas more evenly and appears to wrap itself around a subject. It reality it isn’t, the extreme range of angles the light is now traveling in has a much better chance of hitting the subject in different places. The further you travel away from a diffused light source, the more it will become a point light source and the more a shadow will become apparent.
Using modifiers to redirect light (reflectors, diffusers, gobos, barn doors, grinds, snoots etc…)
Keep this all in mind when placing your lights. Straight line of light will determine shadow direction and diffusion of light source combined with proximity will determine shadow intensity.

Lighting Ratios

Lighting ratios are the main concern when working with two or more lights. The term refers to the ratio of light being put out by one source in relation to another. The ratio is always referred to with the first number being the main (usually the most powerful) light and the second being the fill. The main will always be the number “1” in the equation and the second number being how many stops less +1 the other light is putting out that is reaching the subject. So, a 1:2 ratio will have the main light at full with the fill light having 1 less stop or ½ the power so 1+ 1 (stop less) will give you the 2 in 1:2.
The ratio does not have anything to do with actual power being output from the source. It has to do with the amount of light making it to the subject. Two lights set at the same output levels, but at different distances away from the subject will not have a 1:1 ratio even though they’re putting out the same amount of power. The same applies to lights using different modifiers that can affect the amount of light hitting the subject.
The exception to the rule is if you see a ratio that says something like 3:1. The number 1 still refers to the main light, which is what you are metering for, but the higher first number refers to a light that is being used to overexpose an area. An example would be for a high key shot where you need to ever expose the background in order to blow it out for effect. The stronger lights would then pointed directly at the background, pulling the subject further out to avoid spillover onto the subject from the background lights and allowing the exposure from the main to be unaffected.

Categories of Lights

Main: The main light is just that, it’s the light that produces the light that is used for the exposure of the subject and is the one that is metered for exposure value. It is not always the most powerful light being used. It is always the light that produces the exposure value that will be set on the camera.

Fill: The fill light is the light (or lights) that is used to fill in an area on the subject that is in need of extra light hitting it. This normally means the shadow area opposite from the main, but not always. The fill might also be from a shorter angle to add to the main or from the side to fill more along the edge. The fill will always be a smaller exposure value than the main.

Hair Light: The hair light is hung above the subject and is used to create a smooth highlight along the edge of the hair to give it more separation from the background. The angle it is set in relation to the subject will determine the amount of highlight created. An angle from further back will have a thinner line, straight above will produce a broader line and in front will light the hair fully, but will also have spill off onto the face most likely. You can use a snoot to direct the hair light more accurately, but this will also create a more focused highlight and the exposure value will increase.

Kicker: the kicker light is a small powerful light that is directed to a specific area to really boost the exposure value of it. It is usually directed upwards, but can also be straight or downwards also. The kicker light might have (and usually does) a higher exposure value than the main. This is normally used in fashion photography, so use it to get that look. The light from the kicker should be minimal on the area it is hitting on the subject. Do not over power a subject with the kicker.

Background Light: The purpose of the background light is to provide illumination to the background. It is normally placed behind the subject directed up toward the backdrop. This will give a brighter area behind the subject with a falloff to the edges of the image. Altering the angle and distance of the light in relation to the backdrop will give different effects for it. Closer will produce a brighter area behind the subject with a faster falloff; farther away will give you a softer more gradual falloff. When lighting for a high key situation, then the background light will be set at a higher metered value than the main.

Backlight: Do not confuse with background light. A backlight is used to light the subject from behind and is aimed toward the camera, not the background. The effect you would be going for is edge lighting around the subject. This is mostly visible on someone with lots of hair that is thick.

Metering

When metering for multiple lights, first decide which light is to be the main for exposure. Set that light and take a meter reading for it with no other lights on. Now place the fill light, turn off the main and meter for it. The meter reading should be less than it was for the main. How much less is determined by what the final image result you want is.
If you’re using a back ground light, place it and again meter from the spot that will be centered in the image toward the camera. It should be over, under, or the same as the main all-depending on what the look you are going for is.
If using a kicker…. Turn off the other lights and now meter the kicker as placed in relation to the subject, meter toward the spot where the kicker will hit. It should be slightly over the reading for the main light. How much over is again determined by the effect you are looking for.
Using a Backlight…Meter the light as if the camera will be directly behind the light instead of being in front of the subject who is in front of the light. So, meter toward the background. The reason is to get an accurate measure of the light that will be illuminating the edges of your subject. Light should be over the main if you want a hard “electrical” halo effect. Less if you want a slight differential from the background that is not overpowering.

Sunday, May 9, 2010

Lighting 1

What is Lighting

Photography is ALL about the lighting. Without it, there is no picture taking. Using studio lighting is about controlling the way the light plays across the subject matter to create the image you want. In order to do this the photographer will employ a wide variety of tools to control and create the mixture of light and shadow needed. Incredibly large amount of books have been written about lighting, and it takes years to fully understand it, if ever. This is a short synopsis of general studio lighting usage.

Single Light Usage

Types of Studio Lights

Continuous Source: A light that has a high wattage output. It’s used for lighting a subject for exposure using only the light generated by the source.
Advantages: What you see is what you get. There is no guessing how the light will fall, you see it as is. Easier to control with modifiers such as gobos and barn doors.
Disadvantages: You will be exposing your subjects to very bright lights for the duration of the shoot. Some people are uncomfortable with that. Also, the iris of the eyes will close up, it is considered more attractive for the iris to be dilated. Also, generates a lot of heat. Subjects could be sweating soon. There are newer fluorescent light banks out that don’t produce the heat. Still have the bright lights to deal with and the price ( $2,500 plus)

Strobe or Flash: Most standard lighting used for studio work. Unit consists of a modeling light to show general placement of lighting and a flash or strobe tube that goes off when picture is taken for full lighting power.
Advantages: Most mobile of the lighting. Wide range of modifiers available. Does not heat up a studio as fast. Helps keep the iris of the eye dilated.
Disadvantages: Some guess work on how the final light will be falling. Bright flashes can be frightening to some children. Harder to control with some modifiers such as gobos and barn doors.

Light Modifiers

Light modifiers are used to change the way your source light hits the subject. This can be diffusion, blocking, directing, bouncing, or any other method that alters the path of light. Unmodified light is called direct lighting, or bare bulb.

Basic Light Modifiers

Umbrellas: Umbrellas can be either a reflective or shoot through style. The reflective style will have the light facing away from the subject with the umbrella being used to bounce the light back toward the subject. This will disperse the light creating a larger point source which will decrease the shadows more than a smaller point source. The shoot through umbrellas also diffuse the light, but with a more dramatic falloff toward the edges of the image.

Soft Box: Soft boxes wrap around the light source, bounce the light all around and then direct it out of a frosted diffusion material to create an even soft light. Soft boxes come in different sizes from rather small to large enough to cover an entire car with continuous light. One thing to keep in mind with a softbox is that the closer the light is to the subject, the more the light will wrap around the subject.

Honey Combs: Honey combs are made to fit onto the front of a softbox or other modifiers and create a more directionalized light source. This reduces spill off of light onto areas you might not want them to be on, like the background or a different part of the subject. They are made with different degrees of direction. A zero degree honey comb will give you a straight line light source while a fifteen degree one will produce a light source with a fifteen degree spread.

Barn Doors: Barn doors are just like they sound. It’s a door, or strip of fabric, that is used to cover an area of the light source to keep light from hitting the subject except for where it’s open. If you want to have a small area receive light, like just the face, you would use a barn door to minimize the amount of light to the area you want to light up. More effective when used in tandem with a honey comb situation.

Gobo: A Gobo is a device that is used to cast a shadow onto the subject. The difference between a barn door and gobo is that the barn door doesn’t allow light out, the gobo produces a shadow with the characteristics of a shadow. You get a gradual fall off of light instead of a more direct line of not lighting. Gobos can be any shape and size depending on what you want to accomplish. Some are held into place with a stand and clamps, other times an assistant will hold them.

Reflectors: Reflectors are used to bounce light back in the direction it came from, for the most part. They are made from highly reflective material (usually metallic in nature) and will slightly disperse the light as it is reflected. The thing to remember about reflectors (hence “for the most part”) is that angle of incidence equal angle of reflection. So, if light is hitting the reflector at 45 degrees, then the light will not bounce straight back the way it cam, but will bounce off at 45 degrees in the opposite direction. If you want to fill the shadow under a chin, then place the main light above and behind you toward the subject, then place the reflector under the subject almost straight up and in front. Have the reflector placed so that the light hitting it at the angle is now bounced up toward the subject at the same angle as the light, just from below. If you angle the reflector toward the subject, then light from the source will not be able to hit it and bounce up. Angles are the most critical thing to pay attention to when using a reflector.

Snoot: A snoot is basically a tube that is placed over the light source to create a highly directionalized beam with exceedingly small spill. You need to completely cover the source and then reduce the diameter of the tube to what you want. It is better to have a funnel shape leading off to a tube instead of just ending at the end of the funnel. The longer the tube, the less spread of the light. It is very useful to use as a hair light.

Law of Inverse Proportions: One of the easiest ways to control the amount of light hitting the subject is to simply move the light source further away from it. As light spreads out, there is the same amount to use at all times, the difference is the area it has to now cover. If you have an exposure of f8 with the light 5 feet away, when you move the light to 10 feet away the exposure will now be f5.6. The rule states that each time you double the distance the light now has four times the amount of area to cover, which will result in a 1 stop increase in exposure to compensate. The same is true in reverse. Half the distance equals a one stop decrease in exposure value. This rule is not very precise when used with a directional light source.

Basic One Light Setups

Butterfly: Most commonly used. Light is set up over photographer angled down toward subject creating a minimum shadow just under the nose. Sometimes referred to as a nose line light. Catch light will be centered toward the top of the eye. Does not create much depth for the face. Easiest to use with multiple subjects since shadows from each will fall downward behind them.

Rembrandt: Also called ¾ lighting. Named for the style of lighting Rembrandt used in his work. Light is slightly above and to the side of subject. There will be a shadow falling on the unlit side of the face. A sure sign of this lighting is a small triangle of light directly under the eye on the darker side created by the shadow form the nose and cheek. This lighting will give more depth to a face, careful positioning is needed to keep the dark side eye from getting lost in shadow.

Rim: Light is directed more toward the camera than the subject. Basically you are lighting for the side of the subject that is away from the camera. This is used primarily with profile shots where you want to emphasize the lines of the subject for effect.

Back Lighting: You place a light facing directly at the camera, and then place the subject between the two. Strictly for silhouette shots.

Flat Lighting: The most basic lighting there is. Light is directly above the lens pointed straight at the subject. Called flat because the light hits the subject flat on, no shadows, no contours or depth to subject. This is what you get from a direct on camera flash. Shadow will be directly behind the subject in an outline form. Multi subject close together will have a hard line shadow on them. Try to avoid this lighting if at all possible, it is the most unflattering.

Broad Lighting: Broad lighting is lighting the subject in order to minimize shadow. Most widely used in fashion, glamour and commercial photography. The idea is to illuminate everything and bring out the details with minimum shadowing to maintain depth. Light is almost directly in front of subject and slightly up, a reflector is usually placed under the chin to fill in shadows.

Short Lighting: Most people will benefit from a degree of short lighting. Short lighting is used at more of an angle in order to create more shadow fall off as the subject recedes away form the camera. This will have a slimming effect on people. The degree of short lighting can vary from minimal to more extreme. Judgment is needed in order to decide how much is needed for the particular situation. The light will be at an angle in relationship to the subject and camera. The higher the angle the more short it will be. There is no specific angle to place the lighting since the degree is determined by just how much shadow you want to create.

Metering

One of the most difficult things to do can be metering a lighting setup. An overexposed image can result in lost of detail in the highlights, an under exposed image will suffer in shadow detail. Add into the mix the mood you’re trying to set. Is it a bright open image or a dark moody photo? Same lighting with different exposure can be used for both sometimes.
So, how do you meter? A hand held meter with a diffusion bulb on front of the sensor is best. A light meter will read for your exposure as an 18% gray reflective surface, which is pretty close for skin tones. Keeping this in mind, hold the meter pointing toward the camera lens (or where it will be) not toward the light. You want to measure the amount of light that will be bouncing toward the camera, not the amount being generated total. If you are shooting a rim lighting shot, pointing the meter toward the camera will give you a way overexposed reading. The reason being is that you are now metering for the shadow portion of the image instead of the area you want to expose for. In this situation, meter in the direction the subject will be facing.
The idea for metering is to measure the exposure value of the brightest part of the image as the light will be hitting it. Keep this in mind when deciding what you want the exposure to be for. For a high key set up the meter will be for the subject, not the background. For a low key shot, the metering should be for the very small portion that is getting hit by the light. So, for rim lighting (a low key shot) it will be the ridge of the subject. Since the light will be playing across a very small portion of the area visible to the camera, then measure the side that is away form the camera that will be getting the full value and expose for that since the value will be the same for the small part you will be photographing.
If you are shooting a backlit subject for a silhouette, then measure the light directly instead of toward the camera. You will want the subject to go completely black with the exposure being for background giving it the contrast needed. Meter accordingly.
Most meters are designed to measure a strobe exposure at the ideal setting for the camera sync. Dragging the shutter will change the exposure value by allowing more ambient light to enter in. Keep this in mind when setting the camera. You might have to stop the camera down a bit to compensate.
Meters are pretty well calibrated straight from the factory. Still, they should be tested by shooting. Meter the setup, and then bracket the frames without anything moving. Look at the uncorrected images (or negatives) and determine where the exposure should be. If the image exposes better at a different setting than the meter registered, then adjust the meter to read accordingly. If shooting digital, use the histogram to determine the exposure of the scene and if it’s under or over. DO NOT JUDGE IT BY THE SCREEN IMAGE, THEY ARE NOT CALIBRATED. USE THE HISTOGRAM, NUMBERS DON’T LIE!!!


Some Tech Terms

Ambient Light: Light that is naturally available and usually not controllable. The model lights in the strobes is an ambient light source as is window lighting or any other source outside of what is being used for the lighting setup.

Fall Off: Fall off is the decreasing intensity of the light as it moves further away from the subject or beyond the edge that the light has been directed. It is most noticeable at times around the edges of a wider angled shot that shows up as a vignette.

Spill Light: Spill is the light that affects part of the image that you did not want it too. An example would be if you were lighting a subject for a low key or rim lighting, the light that strays onto the background (which you didn’t want to) is the spill off light from your main light source. It is controlled with a honey comb or barn doors.

Dragging the Shutter: Sometimes it is advantageous to make an exposure longer than the recommended flash sync of the camera. The reason for doing this is to allow more ambient light into the exposure. This will give a slight blurring in the studio along with a color shift from the modeling lights. Doing this can cerate a slightly smoother and warmer skin tone. Another reason would be on location in order to bring the background exposure into alignment with the foreground that was hit by the flash.