One 800W tungsten light (so called "redhead") with daylight nondensity filters, bounced off teh blue ceiling. notise that the projection is a bit washed out because of the extra light.
A small 2 x 10W video lamp with a daylight correction gel used to fill in from the left side. subtle addition and the projection crisp and contrasty.
Shot without adding extra gain. Image is smooth without visible noise.
Shot with 18db. Quality more noisy. This camera, JVC GDV5100, is rather good at low light situations.
Shot in low lux mode, "0 lux" to be specific for this camera, which means that the signal has been amplified even more. Exactly how many dB this would be is unclear. The resulting image is very noisy.
Shot with a cheap consumer camera Sony TRV-80 with automatic gain. We have corrected the levels in post, which also brings out the noise.
The Shoot – Setting up the equipment
Exposure & lighting
Most exhibitions and events tend to be rather dark for cameras. Documenting video installations can for this reason be an extra challenge. Light sensors on cameras have become much more sensitive in the last few years, however it is still important to choose a camera that performs well in low light circumstances.
The eye can detect contrast ratios of 2000:1 whereas video cameras can only detect about 20:1. This number refers to maximum sensitivity. Often the actual useful ratio is much lower. So it is clear that a visitor will experience the space differently from the viewer of the documentation. It remains difficult to capture the nuances and textures of the space on video.
If you are working in a fixed light situation, measure the light correctly and see to it that it captures everything from dark to light and leave it fixed. Be careful that there is not too much contrast between any projections (monitors or screens) and the space itself. In many cases it is good to flood the space with a little bit of light to bring out the space, which is seen and experienced by the viewer but not caught by the camera.
Another tested tip is to use a small, not very strong, camera light (the kind that Sony sells for example) to add a little light to details while filming them. Remember to correct the light with filters. Usually a daylight filter (blue gels) does a good job. You might also need some diffusion filter to soften the light. The same goes for any light you will flood the space with.
Whilst operating the camera use zebra patterns to judge exposure. Remember, if the image turns white (=is overexposed), it cannot be corrected afterwards. The best method is to work carefully to get the right exposure during the shoot; meaning less work in post-production and a better result. If in doubt, underexpose a bit rather than overexposing. Try avoiding too much aperture adjustment mid shot. Usually the aperture changes in steps and this ‘jumping’ can render the image unusable. Also avoid using gain to increase the level of an image. Electronic gain is usually noisy, although the level of noise can vary considerably in different cameras.
If recording in a fixed situation there are tools to monitor the levels of the image while recording. OnLocation (formerly DV Rack) is software that can be run from a laptop and connected via FireWire to the camera and functions as a waveform monitor, vectorscope monitor, a field monitor (that you can calibrate), video analyser, and digital video recorder. This is a useful tool that can also deal with HDV and DVCPRO HD. DV Rack works only on PCs but lately a number of early versions of similar software for Apple Macintosh most notably Scope Box.
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