1. A focus detection apparatus comprising: a focus detection unit configured to detect a defocus value; a first calculation unit configured to obtain a correction value for shifting an in-focus position based on the defocus value by a first method; a second calculation unit configured to obtain a correction value for shifting the in-focus position based on the defocus value by a second method that is different from the first method; a conversion unit configured to convert the correction value obtained by the second method to a correction value of the first method by changing units; a storage unit configured to store the correction value obtained by the first calculation unit or the correction value converted by the conversion unit; and a control unit configured to control driving of a focus lens to a lens position based on a value obtained by correcting the defocus value by the correction value stored in the storage unit, wherein, in the second method, at least one of a plurality of images obtained by driving the focus lens to a plurality of different lens position is selected by a user, and the correction value is calculated based on the defocus value corresponding to the selected image.