Television Broadcasting Tutorial 13


This tutorial looks at technical aspects of camerawork that programme-makers need to understand if they are to successfully record their own professional television content. The technical detail may differ depending on the video camera being used, but the core principles are the same for most situations when filming.

In this case, the detail is specific to students who use a Sony V1 camera and a Manfrotto 501HDV tripod. These pieces of equipment will be referred to directly in this tutorial.

1)    F-Stops

F-stops are units that measure the size of aperture on a video camera. If you can imagine the iris on a camera is like the pupil of an eye, you will start to understand how this works. The brighter the sun, the more your pupils close to make it feel less uncomfortable and to see more clearly. On the other hand, when you’re in a dark room, your pupils open up to their optimum size to make the most of any existing light. This is basically how the iris on a camera works. The brighter the sun on location, the more you need to close the iris on the camera to improve your image and prevent it from being overexposed. While the darker the location, the more you need to open the iris to add light to the image on screen.

When we do this, we manage the F-stops. The image below explains the aperture sizes found on the Sony V1 camera. Rather confusingly perhaps for newcomers to video and photography, the smaller the F-stop number, the bigger the aperture.

When the F-Stop is F1.6, this means the iris is opened to its maximum size for the brightest image possible in dark filming conditions. But when it’s at F11, the aperture is smallest and minimising the amount of light entering the camera in bright conditions. A good grasp of how to use the iris on location will ensure you return with images that are neither over nor underexposed.

On the Sony V1, the ‘Exposure 1’ camera setting (the default setting for Harlow students) links aperture to gain on the iris wheel. But what is gain on a camera? And how can it help?

2)    Gain

If opening the iris still doesn’t solve the problem of a badly-lit location, and the content being filmed is simply too important to miss, then gain is an electronic way to boost the brightness of your image even further. These units are called decibels, signified by the sign dB on your viewfinder/LCD screen, and they go up in multiples of three. But gain has to be used with caution, because too much can make your image ‘noisy’, giving it an unnatural, grainy effect. Only use gain when you have no other choice, and definitely avoid going over 6dB if at all possible. The image will probably appear ‘noisy’ from that point onwards.

The ‘Exposure 1’ setting on the V1 camera enables you to progress from maximum iris to gain by turning the iris wheel. You will automatically see the decibels rise from 0dB to a maximum of 18dB. But I repeat, only use gain as a last resort.

3)    Shutter Speed

The shutter speed varies the amount of time a camera uses to create a video image. A shutter speed of 1/50 is closest to what our eye would naturally see, but visual effects can be achieved by increasing or decreasing either side of that figure. As the shutter speed increases, the amount of light entering the camera decreases. In fact, a speed of 1/120 reduces the light levels by about a half.

For the default ‘Exposure 1’ setting, the shutter speed is locked off at 1/50 for Harlow students (you will see 50 in the bottom right-hand corner of the screen).

4)    Zebras

The zebra pattern – commonly known as ‘zebras’ – is a vital tool to ensure your image isn’t overexposed. The pattern is made up of black and white diagonal lines that appear in the viewfinder/LCD screen to indicate a highlighted area is overexposed (see image below). Most cameras give you the chance to decide which exposure level you want to use.

The Sony V1 has two settings: 70percent and 100percent. The disadvantage of 70percent is that you will often have a large part of the image exposed at this level, so a lot will be covered in zebra pattern. Or you could choose 100percent, which means you will know when parts of your image are about to over expose and lose detail. On the V1, when the zebras are set to 100percent (which is recommended for Harlow students), images that are overexposed lose their colour and definition, and go white with a zebra pattern on them.

At 100percent, to lose the overexposed area, just the roll back the iris wheel until the zebras disappear.

5)    ND Filters (Neutral Density)

A neutral density filter (ND filter) is another way to control light entering the camera and affecting your video image.  On the Sony V1, there are three switch positions (Off, ND1 and ND2) which change the amount of light that passes through the lens. An ND filter has no effect on the colour of the light, but each adjustment changes the exposure by about 2 F-stops (effectively doubling or halving the amount of light). The best way to understand this is to think of ND filters as a pair of shades. They filter light in a similar way.

6)    White Balance

Light consists of three different primary colours. The balance of these colours can change depending on various factors including location and the light available. A video camera is sensitive to these influences, so it’s important to get the white balance right. This can be done manually by zooming into a white card so it fills the frame and setting the white balance to the location where you’re filming. Or by using one of the pre-set settings for white balance: one for daylight, the other set for tungsten light indoors.  You will clearly see the difference to your image when the correct white balance setting is applied. But note: indoor fluorescent tubes are the same as daylight, so you should use that pre-set.

7)    Audio Channels

Good audio is, of course, vital for recording powerful interviews and actuality sound. The points made below build on the information about audio levels already explained in Tutorial 8 (regarding microphones/radio mics and the Sony V1).

  • What is the difference between Mic Level and Line Level? Mic Level is the weak audio signal put out by microphones, while Line Level is a strong audio signal put out by devices such as CD players and audio mixers. The settings in the input connector must match the device being used (which will always be a microphone during student assignments – the default setting for Harlow students).
  • The ‘Record Ch Select’ switch determines how audio from Input 1 and Input 2 is routed and recorded in the camera. The ‘Ch1-Ch2’ option sends audio to Channel 1 and Channel 2, but the vitally important point to note here is that a mic connected to Input 2 will not be recorded. The ‘Ch 1’ setting is different, and allows audio to be recorded separately, with Input 1 audio recorded onto Channel 1 and Input 2 audio recorded onto Channel 2. ‘Ch 1’ is the option students should always choose (pls see the film in Tutorial 8 for more details).
  • +48V Phantom Power: A shotgun microphone, which is used for interviews, is a condenser mic and needs electrical power to function. Electrical power supplied by the camera is known as phantom power.  But a note of caution: some mics may be damaged if phantom power is supplied when it’s not needed. This could happen to radio mics, for instance, which come with their own batteries.

8)    Headphones

Always, always, always use headphones when you shoot…

Volume control for headphones is different to the audio recording level. The first is the level of loudness in the headphones while monitoring sound, but the second is the level at which you record sound into the camera. Adjusting the recording level will change the loudness of the headphones, but adjusting the volume of the headphones will have no effect on the recording level. Make sure you clearly understand how they are completely separate parts of the recording process. You’ll find the volume control for headphones beside the zebras switch on the Sony V1.

8)    Charging Batteries

This is essential preparation for every shoot. When the AC adaptor is plugged into the Sony V1 and the camera is switched off, the battery on the camera will be charged. A light on the camera will indicate it’s charging which goes off when the battery is fully charged.

10)    Manfrotto 501HDV tripod

Below are a link to the instruction manual for this tripod (501HDV Tripod Instructions), plus two videos that demonstrate how to use it. The videos complement films in Tutorial 8 about how to use the Sony V1 and Sennheiser radio mics.

501HDV Tripod Instructions

Below is a link to the second video…

Tutorial – Tripods and Manfrotto 501HDV Setup from BYU TMA105 on Vimeo.

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