Understanding “latitude” is such an important part of the digital filmmaking process. As filmmaker I hear the topic of dynamic range and latitude come up often amongst veteran filmmakers who are use to shooting on film but are now embracing new digital technology. The reason being is that film stock generally has a much easier time handling latitude than digital video cameras. In old Hollywood classics you will see couples sitting in front of a window and you’ll be able to see some of the detail (if the lighting is right) outside of the window. However, the same scene shot with most video camera’s would expose the couple and the interior properly, but would “blow out” (also called “burn out” or “overexpose”) the scene outside the window.
One of the main criticisms about shooting digital video is that the CCD chips in these devices do not handle dynamic range (latitude) as well as film. So what does this mean?
Technically the definition goes something like this: Dynamic range is a term used frequently in numerous fields to describe the ratio between the smallest and largest possible values of a changeable quantity (such as light).
In other words latitude (used interchangeably with dynamic range) is the ability of the camera to capture details in the pixels in the lowest end of the tonal spectrum (i.e. dark shadows) while at the same time capturing pixels in the highest and brightest end of the tonal spectrum (i.e. a bright sky).
Most often the victims of a low dynamic range are exposed lighting sources (such as an exposed bulb or sun) and the sky in the bright end of the spectrum, and darker shadows in the low end of the spectrum. The result is an “underexposing” of the shadows and a “blown out” look to the light areas. Look at the image at the top of this blog post again. Notice the texture of the wall around the florescent lighting is gone. It’s completely overexposed. It’s just a blob of white. Filmmakers call this either “burnt out” or “blown out”.
The reason this is a problem is becuase you’re loosing the digital information in these areas. If you have blown out areas in your raw footage you can’t get this information back in post production. It’s essentially lost information. There is no color, no texture, no detail, no shadows, no objects. It’s just a white void of lost of information.
This is the compromise your digital video camera makes to expose the majority of the pixels in your composition at a reasonable level. However, latitude is getting much better in digital cameras. Generally speaking, the larger the sensor in your video camera the better it is for the dynamic range.
If your camera has good latitude you’ll be well on your way to taking pictures that stand out due simply to the fact that it handles lighting extremes well. Unfortunately at this point, it’s still a feature too few digital video cameras can boast about.
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