$$ \sigma = \sqrt{ \sigma_{shot}^2 + n_{\text{bin}}\sigma_{dark}^2 + \sigma_{quantization}^2 + n_{\text{bin}}\sigma_{read}^2 } $$

Where

Expanding the noise terms:

$$ \sigma(\lambda) = \sqrt{\sqrt{{s_{target}(\lambda)}}^2 + n_{\text{bin}}(i_{dark}\Delta t)^2 + (\frac{1}{\sqrt{12}} \frac{n_{well}}{2^n_{bit}})^2 + n_{\text{bin}}\sigma_{read}^2 } $$

Where