Localization precision versus numbers of incident photons on the diffraction-limited spot. EMCCD cameras show a worse performance with respect to the localization precision when affected by excess noise. Localization precision is also affected by read-out noise of the camera. SPAD array camera with zero read-out noise shows superior performance when compared to cameras with the same PDE, but a higher read-out noise. Therefore, in theory SPAD array cameras with 90% PDE can achieve higher (Poisson noise-limited) localization precision owing to the absence of the Gaussian/normal read-out noise component. For all cameras, the localization precision points are plotted only when the spot detection capability of the corresponding cameras is ≥ 90% for a given number of incident photons to avoid outliers resulting from insufficient statistics.