The test camera is primarily used to evaluate sharpness, color reproduction, illumination, and backlight compensation. Additionally, it measures ball distortion, power consumption, and the minimum operating voltage. Below are the detailed steps for testing sharpness, color reproduction, illumination, and backlight compensation.
1. **Sharpness Measurement**
When testing multiple cameras, it's important to use the same lens—preferably a fixed-focus lens or two variable lenses. The center circle of the test chart should appear on both the left and right edges of the monitor screen. Ensure that the image is clear and accurate. The test chart has 10 vertical lines and 10 horizontal lines, representing vertical and horizontal resolution, respectively. For example, a vertical resolution of 350 lines and a horizontal resolution of 800 lines can be observed. It’s best to use a black-and-white monitor for this test. The camera can be focused on distant objects or the edge of the screen. Using both focusing methods helps observe differences in convergence between far and near distances.
2. **Color Reproducibility Test**
This test should be conducted using a color monitor. First, observe the characters and clothing from a distance to check for any color distortion. Compare the colors of vivid objects to assess the camera's sensitivity. Place a color picture book in front of the camera and check if the images are clear, not too bright or too dark. Also, test the camera’s response to motion. Look for issues like color smearing, lag, or blurring. The test should be conducted under maximum illuminance conditions at 50V, with an additional 10V applied (totaling 60V). Keep the aperture as close as possible during the test.
3. **Illumination Test**
Place the camera in a darkroom with an active 220V incandescent lamp on both sides. A voltage regulator is used to adjust the brightness of the lamp, allowing the illumination level to be controlled from 0V to 250V. This enables the indoor lighting to range from darkest to brightest. When the camera’s aperture is fully open, record the minimum illuminance value by dimming the lamp until the interior becomes completely dark. Then, note the next minimum illuminance value after adjusting the lamp.
4. **Backlight Compensation Test**
There are two methods for this test. One involves placing the camera in a darkroom, turning on the front lamp to its brightest setting, and placing a picture or text under the lamp. Observe whether the image and text are visible without being overly bright. Adjust the AL and AX gear switch to see which setting provides the best result. The second method involves taking the camera outside during daylight. Check if the image and text remain clear despite the strong backlight.
5. **Ball Distortion Test**
Position the test card in front of the camera so that the entire sphere appears on the screen. Check if the sphere appears as a perfect circle or if it looks elliptical. Move the camera closer to see if the center of the circle is magnified. Then, test the edges, corners, and frame at a distance to ensure there is no distortion or arc-like deformation.
6. **Power Consumption and Minimum Operating Voltage**
Use a multimeter to measure the current. Adjust the voltage using a small regulator to determine the minimum operating voltage. This helps identify the lowest voltage at which the camera can still function properly.
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