An imaging system comprising: an optical system having different focus positions for different wavelengths of light; an optical element configured to extend depth of field of the optical system; an imaging device configured to capture an image of an object that is irradiated with illumination light and is formed by the optical system; an image processing unit configured to perform image processing; and a control unit configured to control the imaging system; wherein: the optical element is configured to optically spread a point spread function, the image processing unit is configured to apply a deconvolution process of the point spread function spread by the optical element to the captured image so as to extend the depth of field, and the image processing unit is configured to apply one deconvolution process of the point spread function, which is selected from multiple deconvolution processes; characterized in that the imaging system further comprises: a light source configured to irradiate the object with illumination light of a wavelength that is selected from among multiple wavelengths by control unit; wherein the image processing unit is configured to select the deconvolution process associated with the wavelength of the emitted illumination light; and the control unit is configured to cause the light source to irradiate the object with illumination light in such a manner that a length of an exposure time is changed depending on the wavelength to reduce a variation in contrast between the multiple wavelengths. an optical system having different focus positions for different wavelengths of light; an optical element configured to extend depth of field of the optical system; an imaging device configured to capture an image of an object that is irradiated with illumination light and is formed by the optical system; an image processing unit configured to perform image processing; and a control unit configured to control the imaging system; wherein: the optical element is configured to optically spread a point spread function, the image processing unit is configured to apply a deconvolution process of the point spread function spread by the optical element to the captured image so as to extend the depth of field, and the image processing unit is configured to apply one deconvolution process of the point spread function, which is selected from multiple deconvolution processes; the optical element is configured to optically spread a point spread function, the image processing unit is configured to apply a deconvolution process of the point spread function spread by the optical element to the captured image so as to extend the depth of field, and the image processing unit is configured to apply one deconvolution process of the point spread function, which is selected from multiple deconvolution processes; characterized in that the imaging system further comprises: a light source configured to irradiate the object with illumination light of a wavelength that is selected from among multiple wavelengths by control unit; wherein the image processing unit is configured to select the deconvolution process associated with the wavelength of the emitted illumination light; and the control unit is configured to cause the light source to irradiate the object with illumination light in such a manner that a length of an exposure time is changed depending on the wavelength to reduce a variation in contrast between the multiple wavelengths. a light source configured to irradiate the object with illumination light of a wavelength that is selected from among multiple wavelengths by control unit; wherein the image processing unit is configured to select the deconvolution process associated with the wavelength of the emitted illumination light; and the control unit is configured to cause the light source to irradiate the object with illumination light in such a manner that a length of an exposure time is changed depending on the wavelength to reduce a variation in contrast between the multiple wavelengths.