Media College (Chương 2 : Ánh Sáng)(3) Print
Written by tuyenphuc   
Sunday, 11 April 2010 08:32

Phần 3: Lighting For Video & Television

Video lighting is based on the same principles as lighting for any other visual media. If you haven't done so already, you should read through our general lighting tutorials before reading this page, which deals specifically with lighting issues for video.

Light Sources

All video uses some sort of lighting, whether it be natural light (from the sun) or artificial lights. The goal of video lighting is to choose the best source(s) to achieve your goals.

First and foremost you need enough light. You must ensure that your camera is able to record an acceptable picture in the conditions. With modern cameras this is seldom a problem except in very low light or strong contrast.

Assuming you have enough light, you must then consider the quality of the light and how the various light sources combine to produce the image.

If you have clashing light sources (e.g. artificial interior lights with sunlight coming through the windows), you may find the colours in your image appear unnatural. It's best to control the light sources yourself if possible (e.g. turn off the lights or close the curtains).

When moving between locations, think about what light source you are using. If you move from an outside setting to an inside one with artificial lights, the amount of light may seem the same but the colour temperature will change according to the type of lights. In this case you need to white balance your camera for the new light source.

Contrast Ratio

Contrast ratio is the difference in brightness between the brightest and darkest parts of the picture. Video does not cope with extreme contrast as well as film, and nowhere near as well as the human eye. The result of over-contrast is that some parts of the picture will be too bright or too dark to see any detail. For this reason you need to ensure that there is not too much contrast in your shot. See Camera Contrast Ratio for more details.

Camera-Mounted Lights

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The camera-mounted light is an easy, versatile solution used by amateurs and professionals alike. Typically the light will draw power from the camera battery, although a separate power supply can be used. Be aware that lights which draw power from the camera battery will significantly shorten the battery's charge time.

This type of lighting does not create pleasing effects. it is a "blunt instrument" approach which is really only designed to illuminate the scene enough to allow normal camera operations. However it is a simple, practical solution.

Night-Mode Video Shooting

Some cameras offer a special "night vision" option which allows you to shoot with virtually no light. This mode uses infrared light instead of normal visible light.

This is useful in extreme circumstances when you have no other option. Unfortunately the results tend to be poor-quality monochrome green.

Of course, you can use this mode for a special effect if it suits the content.

Lighting Interviews

The normal rules of lighting apply to interviews. This page covers some general tips specific to interview lighting, whether or not you have your own lights. See our lighting tutorials for more detailed information about lighting technique.

If You Have Your Own Lights

You need to decide whether or not they are actually necessary. Although conventional wisdom says you should control interview lighting yourself if possible, in many situations the existing light will be fine and more practical.

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Shooting outside

The weather will obviously influence your decision. If the natural light is sufficient there may be no need to add artificial light. If you do use your own lights you will need to add the appropriate gels to match your lights to the daytime colour temperature. If the sun is too strong you could find a shady location.

Shooting inside

Find the best location - ideally a room with plenty of space and the ability to control existing light. Unless you have a good reason to use existing light sources, try to eliminate them all (close curtains, turn off lights, etc). Then set up your own lights.

If You Have No Lighting

In many situations you are limited to the available light. This is where a reflector board (pictured) can be a lifesaver. Easy to carry and use, it can create useful lighting effects and compensate for unfavourable conditions. If you don't have a reflector board you can sometimes improvise with other reflective objects.

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Shooting outside

With luck the natural sunlight will be fine, using the sun as the key light. If the sun is low, be careful not to make the guest squint. Strong sunlight creates strong shadows which can be balanced with a reflector.

Shooting inside

Try to avoid mixed lighting, e.g. sunlight through a window mixed with artificial light. Depending on the strength and quality of light sources, you could either turn the artificial lights off or block out the window light.

Overhead lights aren't desirable as they create ugly shadows on the face. If they are all you have you may be able to balance them with a reflector.

Editing Interviews

Before you shoot your interview you must know how it will be edited. For example, if there are going to be lots of other shots inserted you may want to hold a static shot throughout the IV so that these shots can easily be added anywhere. On the other hand, if there is to be little or no editing you may want to vary your shots to maintain interest.

Despite the many different styles of interview, most have a fairly common basic structure. The following example outlines a typical approach:

Establishing Shot

A very wide shot which shows the location. Not always necessary.

2-Shot

A visual introduction to both interview participants (interviewer and guest). Usually a wide shot or MCU.

1-Shot

Begin concentrating on the guest with an MCU and overlay name/title key.

Questions & Noddies

While most of the interview concentrates on the guest, the interviewer is occasionally shown asking and responding to questions.

Cutaways

When appropriate, relevant cutaways can be dropped in.

Cutting Between Interviewer and Guest

The most common edit is the cut between shots of interviewer and guest, whether it be live cuts between cameras or post-production edits.

The natural instinct is to cut exactly between the end of a question and the beginning of the answer. However this tends to look stilted. Try cutting a little before or after the question/answer is complete.

In live multi-camera situations it's easy to get caught behind the action, cutting to the wrong person at the wrong time. This can happen, for example, when you expect one person to speak but another person does. Do not "chase" the person speaking - it's better to have a shot of someone else listening for a few seconds than to cut quickly to the speaker and draw attention to your mistake. If you have the luxury of a wide shot, this can often get you out of trouble.



Back-Cut Questions

If you are using one camera and the IV is to be edited in post-production, the usual routine is to concentrate your framing on the guest during the interview. Then when the interview has finished you reposition the camera to face the interviewer and shoot them asking the questions again. The interviewer is in exactly the same position as they were during the IV, facing the empty space where the guest was (which is of course out of shot). These shots are then inserted into the interview over the original questions. The result is an interview which looks like it was shot with two cameras.

Obviously it's important to record the back-cut questions exactly the same as they were asked during the actual IV. You will usually have a pre-prepared list of questions to help you, but you should also make notes during the IV of any new questions.

Make sure your positioning and eyelines are consistent, as well as microphone placement.

Noddies

"Noddy" is the term given to a shot of the interviewer reacting to the guest. The interviewer may be nodding, smiling, frowning, looking concerned, etc.

Noddies perform two functions.

  • To include the interviewer and show their reactions.
  • To provide edit points.

Noddies are shot in the same way as the back-cut questions. The interviewer faces the same direction and provides a series of nods, smiles and any other expressions relevant to the interview. This is difficult for inexperienced presenters and will cause much hilarity for anyone watching who has never seen it done before.
Note:
If you are tempted to laugh and make jokes at your first professional shoot - don't! Experienced presenters have heard all the noddy jokes a million times and it just shows how new you are.

In the edit suite, whenever you need to remove a segment of the guest's speech you simply inset a noddy to cover the edit. Obviously the noddy must be appropriate - you don't want a shot of the interviewer smiling as the guest relates a tragic incident. This is why you must make sure you shoot the whole range of expressions - so you'll always have the right one for the edit.

Note: For better or worse, noddies can give emotional cues to the viewer. For example, if a guest is reciting some facts and figures, a shot of the interviewer looking shocked suggests to the audience that these figures warrant a strong reaction.

Some More Rules:

When shooting for post-production create clean lead-in and lead-out space, and include information about the IV content.

  • At the beginning of the IV have the presenter record a brief intro and 3-second countdown, leaving the "one" silent, e.g:
    "IV with John Smith regarding environmental contamination, starting in 3... 2.... (silence)..."
    The interviewer then begins the actual interview on "zero".
  • At the conclusion of the interview, pause and don't move. This stops the guest from immediately looking or walking away, providing you with enough time to mix or wipe away to the next shot.

Keep an eye on looking room and direction. When gathering and editing lots of different shots you must be constantly ensuring that everyone is facing the right way. For example, if you shoot your back-cut questions the wrong way the interviewer and guest will appear to be facing opposite directions.

Cutaways and noddies will save your edit. You can't have too many of them.

General Tips for Shooting Interviews

The KISS Principle

When you're starting out shooting IVs it's probably best to keep it simple. It's better to have a boring static shot for 60 seconds than an empty or soft shot. Remember, the important stuff is what the guest is saying, not how creative your framing is.

Dealing with Newbie Guests

Guests who have never been interviewed before can be a challenge, especially if they are very nervous. It's important to reassure them and make them feel comfortable. Here are a few things you might find yourself saying to the nervous newbie:

"Just treat it as a normal conversation. There's no reason for you to worry about anything else that's happening. The best thing you can do to look good for the cameras is to ignore them."

"Don't worry if you make a mistake or muddle up your words - just carry on. It actually happens all the time in interviews, but because it's something the audience is used to seeing in everyday conversations they won't even notice."

"You look fine!"

Note: If the interview is to be edited, you can point out that any serious mistakes can be cut out.

Pace Yourself (and Everyone Else)

Fatigue is the enemy. Interviewers and guests who are tired do not perform well, so be careful not to exhaust them. When preparing the set, use stand-ins to take their place while you set up the shots. Do not ask for multiple takes unless necessary (you will often find the first take is the best anyway).

Clothing

Beware of clothing which is un-camera-friendly. This includes shirts and jackets with fine patterns which produce the moire effect. Dark glasses or caps which obscure/shade the eyes are not good.

Be Prepared

Think about everything that could happen during the interview. Especially if you're shooting off-the-shoulder and there's a chance that your subjects could move around, you need to know how you're going to move. Try to ensure that unwanted bystanders aren't going to interrupt the IV.

Summary

  • Interview technique is a required skill for any serious camera operator.
  • Know what the goal of the interview is and stay focused on that goal.
  • Know the editing requirements.
  • Double-check everything, then do it again.
  • Be prepared for anything.

Lighting with Background Windows

Shooting pictures indoors with external windows is a common issue for photographers and video makers. The large difference in light levels between the room and the outside view make finding the correct exposure a challenge. Video is particularly susceptible to this problem due to it's relatively low contrast ratio.

If you can't avoid having the window in shot, in most cases the only thing you can do is use the manual iris to set your exposure correctly for the subjects in the room. This means that the window will be over-exposed but that's a necessary compromise. If you wish to show the outside view, expose the iris for the window (which will make the room dark).

If you have time and resources available, there are two things you can do to help even out the lighting so it's possible to capture both areas effectively:

  1. Add more light to the room
  2. Reduce the light from the window


(1) Increase the Lighting in the Room

Any extra light you can shine on the subject will decrease the contrast ratio between them and the window.

In some cases switching on the standard room lighting can help, although this often introduces new problems such as clashing colour temperatures and harsh downward shadows.

It's possible that a reflector board could be useful.

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(2) Reduce the Light from the Window

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You can reduce the amount of light coming through the window by placing some sort of filter over it.

In the example pictured here, black scrim (a fine mesh material) is taped to the window. You can see that the background is much more manageable through the scrim.

If the entire window needs to be in shot you'll need to be careful and discreet with the scrim/filter. It can be difficult getting exactly the right fit. If only part of the window is in shot it's a lot easier.

Filters can cause unwanted side effects such as ripple and the moire effect. Being further away from the window helps.

Lighting Effects

Cold / Warm

You can add to the feeling of coldness or warmth by using additional filters or doubling up on gels. Very blue means very cold, very red/orange means very hot.

Moonlight (or any night-time light)

This is an old standard technique which has become something of a cliché. You can make daytime seem like night by lowering the exposure slightly and adding a blue filter to the camera. However a convincing illusion may require more effort than this — you don't want any daytime giveaways such as birds flying through shot. You also need to think about any other lighting which should appear in shot, such as house or street lights.

Firelight

To light a person's face as if they were looking at a fire, try this: Point a redhead with orange gel away from the subject at a large reflector which reflects the light back at the subject. Shake the reflector to simulate firelight (remember to add sound effects as well).

Watching TV

To light a person's face as if they were watching TV, shine a blue light at the subject and wave a piece of cloth or paper in front of the light to simulate flickering.

DIY Lighting Kit

Professional lighting kits for video and photography are very expensive. Fortunately for the budget-impaired enthusiast, it is possible to put together a perfectly adequate lighting kit for less than $US100.

A good beginner's lighting kit should include:

  • Three (or more) lights with stands
  • Reflector board(s)
  • Power cables, extension leads and a multi-box.

The Lights

The standard budget light is the halogen work lamp which can be found at any hardware store or purchased at amazon.com for as little as $US10. These come with or without a stand and range from around 150W to 500W.

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The stand-less units have a small handle and can be rested on any solid surface such as a table or the floor. This is not ideal for your main lights but it can be useful for fill lighting, backgrounds, etc. In any case these units are so cheap that it can't hurt to buy a couple.

Lights with stands are more versatile and you should have at least one of these (preferably two or three). Try to find a stand which goes up to around 2 metres (the height of a tall person). Taller than 2 metres would be even better but this type of light stand doesn't normally go that high.

Some lights (like the W12665 unit pictured) can be used with or without the stand, making them even more versatile.

One drawback of these cheap lights is that the colour of the light is quite yellow. As long as you white-balance your camera this isn't a huge issue, but if you want the best quality lighting you can try one of these solutions:

  1. Purchase a 32K white bulb (ask your hardware supplier).
  2. Place a coloured gel in front of the light to correct the colour.

Speaking of gels, the other big drawback of these lights is that there is no built-in system for mounting accessories like gels and diffusers. You can improvise by creating a wire holder or separate stand for accessories.

You will also find that you can't alter the spread of these lights, i.e. from floodlight to spotlight. This is not a big concern for most people but if you do need this functionality you might need to consider a professional video lighting kit.

Reflectors

Professional reflector boards are used to add or control light in a scene. You can make your own from just about any large reflective object, although the exact colour and reflectivity will obviously affect your lighting. Common suggestions for an improvised reflector include:

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  • Windshield sunshade (pictured)
  • Sheet of foamcore
  • Polystyrene sheet
  • Stiff cardboard, or tin foil on cardboard (try both sides of the foil for different effects)
  • Whiteboard
  • Survival blanket (gold on one side and silver on the other).

Hobby shops have a lot of items which may be of interest. Online auction sites are also worth checking as reflectors can often be found fairly cheap there.

Power

You will need a few power extension cables of varying lengths, plus one or more multi-boxes with built-in trip switches. It helps to have a separate carry case for power cables.

Safety

  • Lights get very hot! Seriously, you can burn yourself badly or set fire to things.
  • Lights can draw a lot of current so be careful not to overload power sources.
  • If you're working outside, use an isolating transformer on your power.

 

Lighting Safety Tips

Keep bystanders away from lights — they are notorious for knocking them over.

Always be extremely careful with the heat created by lights. The barn doors can burn your fingers. Wait until lights cool down before touching or moving them.

Don't handle bulbs with your fingers — use a piece of cloth or something else.

Only use material for gels which is specifically designed for lighting. Don't use paper, tracing paper, baking paper, plastic, etc. Never attach anything to a light which isn't designed for the application.

Make sure stands are stable and loose cables are taped to the ground.

Lights are power-hungry — don't overload sockets. Never plug more than 2Kw of lighting into a domestic power point.

Make sure all lights have adequate ventilation and never cover them.

Tips for Lighting People

Harsh light is not flattering; soft light creates a warmer feel.

Avoid strong nose shadows or any strong contrast on the face. Place the key light on the same side as the camera and fill the shadows.

Avoid reflections from glasses. You may need to adjust the position of the subject and/or lights to do this.

Beware bald heads — they can reflect a lot of light and appear over-exposed. Try weakening or softening the light with a diffusion gel.

Soft light and diffusion helps reduce the appearance of wrinkles.

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