Lens focal length calculator

lensCalculator.m

% required dimensions
standoff = 500; % distance from camera, in [mm]
fovWidth = 320; % width of field of view, in [mm]
fovHeight = 10; % height of FOV, in [mm]

% sensor resolution
sensorXRes = 4096; % widht
sensorYRes = 3072; % height

% pixel physical size
pixelWidth  = 5.5 / 1000; % 5.5 [um] but everything has to be in [mm], so /1000
pixelHeight = 5.5 / 1000;

% sensor physical size
sensorWidth  = sensorXRes * pixelWidth;
sensorHeight = sensorYRes * pixelHeight;

% diagonal size
sensorDiagSize = sqrt(sensorWidth ^ 2 + sensorHeight ^ 2);
sensorDiagSizeInch = sensorDiagSize / 25.4;

fprintf('Sensor diagonal size: %gmm, %g"\n', ...
    sensorDiagSize, ...
    sensorDiagSizeInch);

% aspect ratios
sensorAspectRatio = sensorWidth / sensorHeight;
fovAspectRatio = fovWidth / fovHeight;

if fovAspectRatio > sensorAspectRatio,
    % limited by width
    halfAngle = 180/pi * atan2( (fovWidth/2), standoff);
    maxFocalDistance = (sensorWidth / 2) / tand(halfAngle);
else
    % limited by height
    halfAngle = 180/pi * atan2( (fovHeight/2), standoff);
    maxFocalDistance = (sensorHeight / 2) / tand(halfAngle);
end

fprintf('The maximum focal distance to cover the fov is %gmm\nFan angle approx %g∞\n', ...
    maxFocalDistance, ...
    2*halfAngle)