tv production 1

Here is a basic way to explain how a TV camera works:

Light enters the lens and is converted by the camera's CCD (charged coupled device) into electrical signals that are then re-converted by a TV set into images we can see.

• Lens
• Charged Coupled Device (CCD)
  
• Viewfinder

• zoom in all the way on the target object and focus (if it's a person focus on their eyes)
  
• zoom out and compose the shot
• adjust the focus each time the camera is re-positioned

• Aperture - the lens opening that controls how much light enters the camera's lens
  
• Iris - a lens diaphragm that controls the size of the aperture
  
• F-stop - a scale that indicates how much light is entering the lens, expressed as f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, etc

• The lower the f-stop number, the larger the aperture;
• The higher the f-stop number, the smaller the aperture.

• ND Filter is switched ON under bright, sunny conditions.
  
• ND filter is switched OFF in most indoor lighting environments
  

Gain
This boosts the video signal electronically under low light conditions. When there is boost, detail in the image starts to emerge. But too much Gain adds noise to the image, much like turning up the sound that plays out of speakers. The louder the sound, the more distorted the signal. Video Gain is no different, which is why it is expressed with the same unit of sound -- the decibel. Gain is switched OFF when there is adequate lighting, and switched ON when the lighting conditions are less than ideal. But don't use too much Gain to avoid adding noise to the image.

Shutter Speed
This portrays how motion appears in the image. If the shutter speed is slow, more motion is captured in the image (and the motion appears to be blurred). Shutter speeds below 1/60th of a second can cause the image to appear surreal or dreamlike. Faster shutter speeds will appear to "freeze" motion (there is little or no blur in the motion). The faster the shutter speed the less light can enter the lens. The slower the shutter speed, the more light can enter the lens. The minimum shutter speed should be 1/60th of a second. 

Zebra Stripes
These stripes appear in the viewfinder when the image is over-exposed. The lines appear only in the viewfinder image and are not recorded on to the final image. Zebra stripes are a great way to assist you when setting the proper exposure. It's fine to see zebra stripes in parts of the image (highlights on clouds, lamps, foreheads, etc). The goal is to change the exposure to get rid of zebra stripes that appear on the subject, namely the face.

• Is the ND filter ON or OFF?
  
• Is the Gain ON or OFF? 
• Is the shutter speed greater than 1/100th of a second? If so, then reduce it to allow more light to enter the lens.
• Finally, adjust the Iris to control the size of the aperture.
  

• Shallow Depth of Field - mid-ground and background objects will be out-of-focus (blurred), while the foreground remains in focus;
• Great Depth of Field - everything in the image is in focus

• Wide Angle = Great Depth of Field
• Narrow (Telephoto) = Shallow Depth of Field

• large f-stop numbers = greater depth of field
• small f-stop numbers = shallow depth of field

• depth of field is shallow with close-up shots and low light
• depth of field is greater with long lenses and lots of light

• better for movement (hand-held)
• makes objects close to the camera look relatively large; objects further away look small (exaggerates distance)
  
• gives forces perspective adding to the illusion of distance and depth
  

• more difficult to keep in focus with movement
• depth of field is shallower
• ideal for studio set-ups so in-focus objects are set off against a slightly out-of-focus background

• magnifies background objects
• gives the illusion that the distance between foreground, mid-ground, and background is decreased (compresses distance)
• because the distance between mid-ground and background appears compressed, the narrow lens gives the illusion of reduced speed of objects moving towards or away from the camera
• bad for hand-held shots because even small movement can change the field of view dramatically

• contains hundreds of thousands of pixels that are arranged in horizontal and vertical rows
• takes a certain amount of pixels to make a recognisable image
• pixels are electrically charged (video signal)
• in digital TV (DTV), the video signal gets digitised

• all TV pictures are a mixture of RGB
• there is a separate electron beam for each colour
• the CCD separates in-coming light into RGB

• the number of pixels in the CCD or TV screen
• the quality of the lens
• the number of scanning lines measured by the way lines are stacked, i.e., NTSC = 525 lines of resolution, HDTV = 1080 lines of resolution.

• Low Kelvin degrees (3200 K = indoors = light appears reddish)
• High Kelvin degrees (5600 K = sunny day = light appears bluish)

There is more blue in this image                                             There is more red in this image

Contrast
The best way to remember contrast is that it describes the range between light and dark. High contrast appears when the distinction between bright and dark areas in the image are great. Low contrast occurs when the amount of lighting in the image is roughly similar (grey tones).

Shading
A term that is used during studio productions when a video operator (VO) pulls down excessive light that enters the camera. Using waveform monitors to make sure the white levels remain according to transmission standards, the VO "shades" cameras by closing the aperture a little at a time.