You only need to adjust the focus if your lenses are really out of focus. Now with the 70D’s and the 5DMkIV’s not only can I check the focus but I can adjust it. I have always checked my lenses to know if they are working correctly. In the past we would have to bundle up the camera body and lens(es) and send them away to be adjusted. This way you know if you have a problem lens and, as mentioned above, some cameras have a menu (micro focus fine adjust) that allows a photographer to make changes to the focus setting without sending the camera or lens away. So what is a lens focus check? It is a way to check to see that when your camera says that the image is in focus, and thereby should be sharp, that it is actually in focus and sharp. If the focus is really out and you do not have the ability to adjust the focus you will have to send your camera and lens away. Now before I go any further let me say not all cameras can do what I am going to describe in that you can adjust the focus yourself. I was doing a focus test on my lens and made a video about a way of checking the focus on your lenses (links below) One of the great things about winter in southern Alberta Canada, especially when it is a blizzard, is that I have time to catch up on projects.
