Eye-sight of individuals varies a lot. Some use spectacles and others don’t. Even those who do not use spectacles, end up with reading glasses after around 40 years of age. Camera manufacturers understand this and therefore they provide ways to incorporate minor adjustments to the camera, in sync with the requirements of the varying eye-sight.
Very frequently I come across the comparison of eyes and camera. Photography students are frequently taught that the camera works like a human eye and medical students are taught that the eyes work like a camera. This gets one wondering how are they similar and where does each of them stand out.