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MillimeterSoftware Field Monitors, Part 1
May 12, 2008 12:00 PM, By Jan Ozer
Figure 2. Vectorscope, RGB Parade and Luma Histogram.
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Let's look at a three more scopes that many shooters also like to have at their disposal to help fine tune their image. Note that I've changed programs and images for Figure 2, now showing ScopeBox shooting the Cambelle's test image from DSC Labs.
The Luma Histogram, shown on the top left, shows the same information as the Waveform Monitor, but in a different way. Specifically, it also shows brightness values (also called luminance, hence the Luma in the name), but on a scale of 0 to 255, with 0 being complete black on the left, and 255 being complete white on the right. Rather than showing the location of the pixel in the frame, the histogram shows the number of pixels at each value. For example, the two peaks in the figure are probably the models' dark hair (on the left) and the blue sky on the right.
What this chart tells me is that the luminance values are grouped around the middle, which usually means that the picture will lack contrast. This is to be expected in a picture on a wall lit by fluorescent lights; in the real world, I'd shift the lights around to create darker and brighter regions.
If changing the lights didn't produce the desired results, I'd also mess with the Canon XH A1's custom settings, such as the black stretch, knee, and pedestal controls. Having the detailed and immediate feedback from the histogram and waveform, as well as a 17in. preview screen, courtesy of my MacBook Pro, gives me a lot of confidence to experiment that I don't have when I'm relying solely upon my LCD preview screen.
The other two scopes, RGB Parade and Vectorscope, help producers check color values in their signal. I tend not to use these scopes, and just wanted to let you know that they are typically available in this class of product. Wikipedia has great descriptions for both scopes, so if you need more information, check www.wikipedia.org.
Figure 3. OnLocation's Audio Spectrum Analyzer.
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In addition to these video scopes, most products in this class also offer audio analysis tools such as OnLocation's Audio Spectrum Analyzer. This measures the input of 32 bands of audio, which is great when you're recording musical events and want to make sure that your microphones are capturing both the bass player and flute. As you can see, there's also a master volume meter and clipping indicator that quickly let you know that your overall are too high.
