Apparatus for the capacitive determination and/or monitoring of at least the level of a medium in a vessel, wherein said apparatus comprises a probe unit with at least a probe electrode, and an electronics unit, which is designed to apply an electrical transmission signal to the probe electrode, and to receive and evaluate an electrical response signal from the probe unit, wherein the electronics unit is designed to perform a frequency search and to apply the frequency search to the probe electrode, wherein the frequency search features a large variety of consecutive discrete exciter frequencies located within a predefinable frequency range, characterized in that the electronics unit is designed to determine - on the basis of the response signal and using the frequency search - an optimum measuring frequency which is within the predefinable frequency range and defined by current application parameters, wherein the associated response signal most accurately represents the level, and wherein the current application parameters are environmental parameters, particularly the level, the physical properties of the medium, or deposit buildup on the probe unit, and the design of the probe unit, as well as the installation geometry, in that, for each frequency of the transmission signal, the electronics unit is designed to determine and store - on the basis of the associated response signal - the value of at least a measurable characteristic variable of the response signal which depends on the current application parameters and can be determined directly from the response signal and/or at least a dependent variable which can be calculated from at least a characteristic variable, wherein the electronics unit determines the phase shift between the transmission signal and the response signal and the admittance or the value of the response signal as the characteristic variable, and particularly determines the capacity and/or the level of the medium as the dependent variable calculated from the characteristic variable, in that the electronics unit is designed to constantly apply frequency searches to the probe electrode, and in that the electronics unit is designed to determine the level from the response signal associated with the optimum measuring frequency. wherein the electronics unit is designed to perform a frequency search and to apply the frequency search to the probe electrode, wherein the frequency search features a large variety of consecutive discrete exciter frequencies located within a predefinable frequency range, characterized in that the electronics unit is designed to determine - on the basis of the response signal and using the frequency search - an optimum measuring frequency which is within the predefinable frequency range and defined by current application parameters, wherein the associated response signal most accurately represents the level, and wherein the current application parameters are environmental parameters, particularly the level, the physical properties of the medium, or deposit buildup on the probe unit, and the design of the probe unit, as well as the installation geometry, in that, for each frequency of the transmission signal, the electronics unit is designed to determine and store - on the basis of the associated response signal - the value of at least a measurable characteristic variable of the response signal which depends on the current application parameters and can be determined directly from the response signal and/or at least a dependent variable which can be calculated from at least a characteristic variable, wherein the electronics unit determines the phase shift between the transmission signal and the response signal and the admittance or the value of the response signal as the characteristic variable, and particularly determines the capacity and/or the level of the medium as the dependent variable calculated from the characteristic variable, in that the electronics unit is designed to constantly apply frequency searches to the probe electrode, and in that the electronics unit is designed to determine the level from the response signal associated with the optimum measuring frequency.