Charting Your Camera - Creative COW

The vectorscope reading and chart output for 100% chroma, or saturation.

The vectorscope reading and chart output for 75% chroma, or saturation.

YES VIRGINIA, YOU DO NEED BOTH A WAVEFORM AND A VECTORSCOPE

If you have a camera that supports adjusting a camera's native color matrix, where on your camera do you actually perform the adjustments? The locations of these controls, plus the options available in these matrix settings are so varied that it is all but impossible to keep up with each and every camera's options. If you don't want to spend a lot of time digging through menus on your specific camera, consider reading the manual.

After a chart and some idea how to read it, and where on your camera you can make some of these adjustments, the last piece of the calibration puzzle is to be able to read and display the output signal on a waveform and vectorscope.

A waveform monitor is a special type of oscilloscope, typically used to measure and display the level, or voltage, of a video signal with respect to time. While a waveform monitor measures the overall characteristics of a video signal, a vectorscope is used to specifically visualize chrominance.

There is a lot to learn about the specifics of reading these, but at the most basic, the distance from the center of the vectorscope increases the Saturation, and direction from the center of the scope defines the Hue (overall color).

For the record, you do have these tools residing in applications like Avid Media Composer, Premiere Pro and Final Cut Pro, but for purposes here, the need for realtime analysis of the signal is paramount. I have used Adobe's OnLocation in CS5 to check a camera onset in the middle of a cornfield and while not ideal conditions, I was able to fix my problem.

Whichever system you use, the pictures of scopes shown here will look similar to what you have. Note that, out of the box, the default setup for most digital cameras is to have the Chroma and Luma locked at somewhere around 75% to keep the camera settings within the Rec709 limits for broadcast HD. You can see how 75% chroma, or saturation, appears on a vectorscope in the top left image above. Below that, you can see how the chart that corresponds to that level will look.

In the top right image, notice how the vectorscope appears after adjusting the camera to 100% for maximum color saturation. Once again, below that, you can see how this affects the look of the chart.

Having just that little extra bit of color control can solve a wide range of issues, yet this level of calibration is really about understanding that what comes out of the box, as designed at the factory may not always be the best for every person in every situation. Having the knowledge and power to be able to customize your camera settings offers you a wider variety of tools and a variety of looks, while also offering nearly complete control over any and all situations.

The Fairburn 3D chart, designed for DSC by veteran cinematographer B. Sean Fairburn. Photos courtesy DSC Labs.

LENS SHADING

If your camera has interchangeable lenses, and you regularly have lenses from different companies in your kit, you should perform what is called "White Shading" or "Lens Shading" on your camera. This is camera-specific process that most often requires that the user gain access to the maintenance or service menus for your specific camera. A quick Google search for "XX camera, white shading" revealed the exact shading methodology for more than two dozen different cameras, so finding the info specific to your camera is not difficult.

Indicators that a full "White Shading" is required on your camera are evident when you have image highlights that have variable color "fringing" or "edging" with a colored band at edge areas having extreme contrast.

Essentially, white shading is the process of setting every pixel to a common level of white reference based on the specifics of the specific lens you are using. While lenses from the same manufacturers tend to have similar color characteristics, lenses of differing types -- i.e., primes vs. zooms, may have differing color rendering.

The way to set this is to point your lens at a perfectly even and white surface like the plexiglass I mentioned earlier. Or you can use an "integration sphere," which is like the inside of a huge ping pong ball.

Auto white balance your camera and then set the exposure to 70% IRE, and then perform the white shading. This will set an offset for each and every photosite on the three sensor chips to create a "perfect" white reference for that specific camera and lens combo.

HOW TO MESS UP YOUR CAMERA USING THESE SIMPLE STEPS

If you are thinking that this sounds complicated, you are absolutely correct. That is one of the reasons why this process has been reserved for the higher end broadcast cameras until recently, working under the assumption that trained technicians are performing these tasks. But as cameras of every price range become more powerful, and more different kinds of cameras are being used on more different kinds of productions, it is absolutely critical that you have some idea of what you're getting into when you need to use them with each other.

I want to reiterate that each and every camera manufacturer does this differently. I suggest trying to Google your camera type and model for the specific process for each camera, as I was able to find versions for most modern cameras.

As a reminder, neither I nor Creative COW is responsible if you try to do this and things go wrong. Always know how to do a factory reset on your camera. It is by far the best way to get your camera back to a working state.

If you're up for it, you can try again from there. But if you are not sure that you are capable of doing these modifications yourself, contact your local rental house -- they will have people that can assist you with this process, though expect a fee for them to handle the process for you. Whether you do it yourself or turn to a specialist, being able to rely on the images your camera captures, and working with them most effectively and efficiently in post, starts with calibration.

Gary Adcock
Chicago, Illinois USA

Gary Adcock is the principle information architect at Studio 37, for all types workflows for Production and Post digital film projects as well as a working I/A 600 DIT and 3D Production and Post Stereographer. He has also been the Technical Chair for NAB's Director of Photography conference since 2007. You can find Gary hosting in Creative COW forums for AJA Kona, AJA io, ARRI, Panasonic VariCam, RED Camera, Stereoscopic 3D, Apple iPad, Glue Tools, and more.