A method for counting photons using a photomultiplier includes obtaining a measurement signal from a raw signal produced by the photomultiplier by correcting the raw signal for a noise signal and/or an offset, wherein an incident photon produces a pulse in the raw signal. The measurement signal is integrated over time to form an analog integrated measurement signal. A number of photons that are incident in the photomultiplier is ascertained by comparing a value of the analog integrated measurement signal to an integral proportionality value which corresponds to a specific number of photons incident in the photomultiplier.