The resolution of a microscope is the ability to distinguish between two closely spaced objects. It is determined by the wavelength of light used and the numerical aperture of the objective lens. The numerical aperture is a measure of the amount of light that is gathered by the objective lens.

The magnification of a microscope is the ratio of the size of the image to the size of the object. It is determined by the focal length of the objective lens and the focal length of the eyepiece lens.

So, a microscope that enlarges an object 400 times does not necessarily have a resolution of 400. The resolution of the microscope will depend on the wavelength of light used and the numerical aperture of the objective lens.