A wavelength detecting apparatus capable of detecting the main wavelength of the light coming into an image capture apparatus and a focus detecting apparatus using the same are disclosed. The wavelength detecting apparatus may include a spectral unit which separates the incoming light according to the respective wavelengths, and may focus the separated light onto a sensor. The main wavelength can be determined based on the wavelength distribution sensed by the sensor. The determined wavelength can be used to further determine amount of adjustment to be made to the defocus amount to compensate for the chromatic aberration associated with the wavelength of the light illuminating the source.
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