Historically, analog video cameras fell into neat categories. Professional cameras were big, expensive, well made, and produced high-quality video, whereas consumer cameras were small, very inexpensive, had an inferior image, but above all were easy to use. Then came digital video and everything changed-and so much the better for low-budget independent filmmakers. Today, you can find many cameras offering ultra-high-quality resolutions, exceptional lenses, and precise user control over exposure, color space, white balance, aspect ratios, and frame rates, as well as professional audio and video input/output connectors, for around $4,000 or less! The quality-to-price relationship is so great that these cameras are not used strictly by students and shoestring budget filmmakers, many profes-sionals and commercial production houses have adopted them as well. These high-quality, yet affordable, video cameras may be too complex for the average consumer, but they are excellent when a polished and controlled look is important and a high-end, professional rig would be overkill in terms of physical size, complexity, and expense. In short, the line dividing professional-quality gear and nonprofessional access is fading – virtually anybody can create HD broadcast-quality content or even 4K projects on a budget. Sure, there will always be a line of ultra-high-end professional cameras so technologically advanced and tricked out that buying one requires a second mortgage (see page 233), just as there will always be a line of super cheap consumer cameras that do everything easily but nothing particularly well, but the range of cameras between those two poles are getting better and more affordable.
High Resolution and Color Figures
Both professional and mid-level video cameras, like this Panasonic AU-EVA1, have the following basic features: (a) camera body, (b) function control panel, (c) lens, (d) viewfinder and/or LCD viewscreen, (e) record media bay, (f) audio/video I/O ports, and (g) the media bay.The external functions panel on cameras designed for filmmaking often include: (a) aperture/iris control, (b) ND filters, (c) white balance and gain, (d) menu access, (e) manual audio level pots.SDXC cards (left) are always clearly labeled with: (a) storage capacity, (b) data transfer speed, and (c) class rating; CFexpress Type B cards for recording video (right) are labeled with (d) capacity, and a “Video Performance Guarantee” rating (e) that identifies their minimum sustained write speeds.Common video ports found on cameras usually include an HD-SDI (a) and SDI output and video output for monitoring (b), a HDMI port (c), and USB ports (d).A photo presents seven labeled connectors depicting an audio jack, X-L-R connector, B-N-C connector, H-D-M-I plug, mini H-D-M-I, micro H-D-M-I, and a U-S-B connector arranged in a row.The basic image path through a digital camera. Light enters the lens and creates an analog electronic exposure on the image sensor pixels (a), which is converted into a digital signal by an analog/digital converter (b), and then sent to the digital signal processor (c) for color encoding, compression, etc. The processed digital video signal is sent to the record media (d) and the video output ports for image display.The surface of a CMOS chip is coated with millions of pixels. Every single pixel contains a micro lens (a) over the Bayer color filter layer (b) that focuses filtered light onto a photodiode (c). Every pixel also has the transistor circuitry necessary to convert that light energy into an amplified electronic signal (d) which is sent to an on-chip analog-to-digital converter (e) to create the digital image readout.A Bayer Pattern Filter (a) separates the light falling onto a sensor into the three primary colors in a mosaic pattern. This assures that each pixel on the sensor registers only one color (b). The separated colors are later merged by the digital signal processor in a process called demosaicing, to create the full color image. See the color insert.Image sensors come in a variety of sizes. This image shows a comparison of the capture area of some common CMOS sizes for digital video.Bit depth is an important aspect of digital image quality. Shown here are a 2-bit black-and-white image (top left); a 4-bit image with 16 shades of gray (top right); an 8-bit image with 256 colors (bottom left); and a 24-bit image with 16.7 million colors (bottom right). See the color insert.Spatial compression (left) identifies blocks within a frame that contain identical color information and will record only one pixel’s color value to share across the block while tossing out the redundant visual data. Temporal compression (right) will record the color values of the first frame in a shot and will then duplicate that data across subsequent frames in areas that do not change, allowing the codec to eliminate redundant information that is repeated frame, after frame, after frame. See the color insert.Chroma subsampling compression reduces data by sampling blue (Cb) and red (Cr) information in only two pixels (4:2:2) or only one pixel (4:1:1) and sharing that information across the block of four pixels. Luminance information (Y) for every pixel is always sampled. The ratio 4:4:4 indicates that the color information is not being compressed.RAW, uncompressed, and Log footage are output from the camera at different stages. RAW footage comes directly from the ADC and is not yet a fully formed video signal, uncompressed video is output from the DSP but has not undergone any codec compression, and Log footage emerges from the DSP as a complete and compressed video signal, but with a flat gamma profile.The flat gamma profile of the Log format makes the original footage appear dull and gray (bottom) but with color grading, or the application of a LUT, the Log format will yield improved color opportunities over standard HD Rec. 709. See the color insert.Some video camera functions are embedded inside menus accessible on the LCD screen (left), while other, more commonly used features (like the manual overrides for focus and iris), are found on the camera’s body (right).All video cameras have a way to balance the image sensor to a variety of color temperatures. For manual white balancing you must first switch off the auto white balance function (a). A user can manually set color temperature balance for each scene (b) or recall daylight and tungsten presets (c).To speed up the color correction process in postproduction it’s recommended that you shoot a color chart with flesh tones at the head of every card for reference. See the color insert.
