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Putora Gray Scale Sharpness Indicator Chart (11.75"x14.75") |
This 10.5" x 13.25" chart provides extremely accurate 5-stop, 11-step gray scale for testing video formats; it can be used as a base for colorimetric or exponometric evaluation.
Additional Information
The Sharpness Indicator Gray Scale chart provides an extremely accurate, 11-step, TV compensated gray scale.
• In addition to the 11-step scale, the chart incorporates several other components: a continuous scale, a Contrast Indicator surrounded by 18% gray (in the center), a Multi Cycle Scale for rapid sharpness assessment (at the bottom), and . . .
• Both sides of the chart are lined with gradual steps of "siemens stars" handy for brief back focus setup. The chart also has a deep black patch made of black velvet.
• Charts are made on matte photographic paper that will maintain the chart’s integrity over a long period of time. Competing test charts that are painted are subject to chemical decomposition that rapidly changes the density values and color information.
The Sharpness Indicators are made up of test-targets with concentric circles at various frequencies printed on a Reference Field Level background. The gray background has the same reflectance as the average reflectance of the targets. When a target appears to disappear and blend with the background, it indicates that the target is beyond the sharpness of the system being tested. Because the targets 'pop' into focus, this system is far superior to standard Air Force bar-type charts.
Use it solo to check sharpness and back focus of any optical system. Use it to check critical focus on a production set. Among the uses are the ability to instantly determine the resolution of any lens/camera system, set critical focus at any distance, set or check back-focus of any lens/camera system, and, compare resolution between various film and video formats.
The manual included with the charts goes into great detail on how to use and evaluate what the Sharpness Indicator charts provide.
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| 06/05/2009 |
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| HOW DO YOU USE THE MC BAR ON THE PUTORA CHARTS? |
The MC are based on cycles or line pairs (one black and one white line).
It was originally designed for the 2/3" broadcast format that is with horizontal line of 8.8mm across the sensor.
The 2/3" camera has to be placed so the two arrows on the ends of the MC bar are just outside of the frame without cutting in the MC bar.
Setup this way the MC 1 represents 80 cycles, if it filled the entire line you would have 80 pairs of black and white lines and you would need a minimum of 160 horizontal TV lines to resolve this pattern.
MC2 is 160 cycles and 320 horizontal TV lines
and so on to MC12 with 960 cycles and 1920 horizontal TV lines.
If you need a value in line pairs per millimeter, 80 cycles / by 8.8 gives us 9 lp/mm for MC1, 18.2 lp/mm for MC2, 27.3 lp/mm for MC3, 36.4 lp/mm for MC 4, 45.5 lp/mm for MC5, 54.5 lp/mm for MC6, 63.6 lp/mm for MC7, 72.7 lp/mm for MC8, 81.8 lp/mm for MC9, 90.9 lp/mm for MC10, 100 lp/mm for MC11, 109 lp/mm for MC12
Again theses values are valid for a 2/3" camera setup as described above.
If your sensor is of a different size and you fill the screen with the MC bar, a corrective factor has to be applied.
Putora HDTV Chart Instruction Manual.pdf |
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