Ross Synergy 100 MD, Operator'S Manual

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7–30 • Keying Synergy 100 MD Operator’s Manual (v7.2 MD-S100)
elements on the Background by adjusting the Positive Hue and Negative Hue of
the Background .
9. Are there Shadows in the Chroma Key?
•
No
— Increase the Translucency Gain to increase the amount of detail, or decrease
the Translucency Gain to have a cleaner Background .
•
Yes
— Increase the Shadow Gain to increase the amount of detail, or decrease the
Shadow Gain to have a cleaner Background .
This completes the procedure for fine-tuning an UltraChrome Chroma Key.
Chroma Key Memory
Unlike Self Keys, Chroma Keys do not retain the clip and gain values with each crosspoint. Instead,
there is only one set of values associated with the entire switcher at a given time. Therefore, each time
you change the source of the Chroma Key, you will have to re-clip the Key as outlined above.
Chroma Key Lighting Tips
Achieving a good, clean Chroma Key is often considered one of the most challenging exercises in a
studio. There are several elements that contribute to an effective Chroma Key including, lighting,
distance of the talent from the background, type of background used, and the type of camera used.
However, lighting is often considered the most important. Here are a few lighting hints which you
may find helpful when setting up your Chroma Key.
Lighting the Background
• There are several different kinds of lights typically used to light Chroma Key
backgrounds. The most common are, cyclorama lights, soft lights, scoops, florescent
lights, HMIs, and umbrella lights.
For the most part, the one thing that they all have in common is the fact that they are
“fill” type lights, as opposed to “Key” lights. These lights provide an even, diffused, flat
light, which is critical in lighting Chroma Key backgrounds.
• For best results, lights are usually hung in an even pattern from a grid above the
background but space requirements may dictate the lights be positioned on stands beside
the background. If side lighting is used, ensure the lights are positioned at equal
distances from the background being lit, in order to achieve balance.
• The number of lights used to light a background is directly related to the size of the
background surface. Therefore, a larger, longer surface requires more lights than a
smaller one. But whatever size of surface you are lighting, the most important point to
remember is the background should be lit as evenly as possible to avoid “hot spots” in
the Chroma Key.
• When lighting the background, experienced lighting directors will check the background
for hot spots, adjusting and readjusting the lights, using either a waveform monitor or a
photographer’s light meter. Waveform monitors are most useful since they display a
graphical representation of the video level and any small variation in light level is
immediately apparent. On the other hand, a light meter in the hands of an experienced
professional can achieve the same results.
• Generally speaking, best Chroma Key results are achieved with an even level of light on
the background in the area of 60 – 75 IRE on a waveform monitor. However, conditions
specific to your application may dictate a value outside of that range.