Ted Cousins
Member
I've often wondered exactly how it does that.
After much formula manipulation, it says:
"Camera manufacturers build light meters adhering to international standards (like ISO 2720:1974). For a standard handheld meter or camera sensor matrix, typical calibration constants are:
Camera manufacturers build light meters adhering to international standards (like ISO 2720:1974). For a standard handheld meter or camera sensor matrix, typical calibration constants are:
K (Reflected Light Constant) approx 12.5
C (Incident Light Constant) approx 250
Plugging these exact industrial constants into our equation:
R=pi x 12.5/250= approx 0.157 This proves that the system is hardwired to expect a surface reflectance R of roughly 15.7% (mid-gray)."
Not 18%, not 12.5% ...
Hope the link works ... scroll up to see beginning ...Google AI said:
After much formula manipulation, it says:
"Camera manufacturers build light meters adhering to international standards (like ISO 2720:1974). For a standard handheld meter or camera sensor matrix, typical calibration constants are:
Camera manufacturers build light meters adhering to international standards (like ISO 2720:1974). For a standard handheld meter or camera sensor matrix, typical calibration constants are:
K (Reflected Light Constant) approx 12.5
C (Incident Light Constant) approx 250
Plugging these exact industrial constants into our equation:
R=pi x 12.5/250= approx 0.157 This proves that the system is hardwired to expect a surface reflectance R of roughly 15.7% (mid-gray)."
Not 18%, not 12.5% ...
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