|Media College (Chương 2 : Ánh Sáng)(3)|
|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.
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 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.
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.
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.
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.
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.
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.
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.
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:
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.
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.
"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.
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.
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.
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).
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.
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.
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: