0902 Getting the most out of your camera should be repeated until the zebras cover the entire image. The lens aperture of the camera should be adjusted to between f4 and f5.6. To do this, adjust the physical distance of the camera to/from the AmbiLight to achieve the f-stop range. In doing this process it may be necessary to adjust the AmbiLight source to produce an evenness of the light and the above steps may need to be repeated. Once the set-up is complete, perform a White Balance of the camera and use the light meter and waveform monitor to check that the white balance has been properly performed. The colour temperature readout after white balancing should read 3200K and it maybe necessary to adjust the camera's Red and Blue gain settings to achieve this. Slightly defocus the lens to further soften any diffusion error. In the shading menu of the camera, adjust the vertical and horizontal saw to 50. The vertical and horizontal pars should be set to a 0 as a baseline. If these numbers are off, the gamma controls may be on and must be disabled. HD Camera Measurements Recap Part 1: In part 1 of this knowledge series we discussed the requirements for making correct white shading measurements in terms of the equipment used. Part 2 now will focus on performing the actual measurements and making sure that we achieve optimum linearity and dynamic range. Courtesy of Tektronix EMEA Getting the most out of your camera, Part 2 luminance spot meter and adjust the AmbiMirror and light source. The optional AmbiGrid (Figure 1b. Equal rectangles on a transparency, sit in front of the diffuser) facilitates separation of the diffuser area into equal quadrants. Aim the luminance spot meter at the centre of each rectangle and recording the luminance and colour temperature values in each quadrant. Adjust the barn doors and vertical distance from the DSC AmbiLight to the AmbiMirror as required until the light output in each quadrant is as even as possible. Measurement deviations of +/- 0.5% are typical; however deviations of 1% or more are not uncommon. The gain on the camera should be set to 0 dB. Also, ensure that the knee and other camera gamma controls are set to off. Position the camera in front of the Ambi Diffuser panel and zoom in to overshoot a bit in order to use the centre of the panel. Ensure the camera lens is set to Manual Iris mode and the Zebra setting is adjusted to 95% so that the zebras cover the entire image. Note that if a spot meter has not been used to ensure evenness and the zebras do not cover the entire image then the light may not be even and the above steps White shading measurement P >> 29/1/09 17:27:27 Page 36 of 100 TV-BAY027JAN09_MAG.indd 36 primera2009_tv-bay_UK ower up the camera, waveform monitor and DSC Ambi Illuminator and then connect the HD-SDI output of the camera to the waveform monitor. Allow a few minutes for the light source and the system to stabilise to normal operating temperature before starting your measurements. The Ambi Diffuser has a vertically adjustable light source, Figure 1a. However, to achieve greater precision, measure the light output from the device with a Figure 1a. Ambi Illuminator with no pattern. Figure 1b. Ambi Illuminator with grid over transparency.