I used the Canon FTb and F1, then a Nikon FM10, switched to digital Nikon bridge cameras, and switched back to Canon with the 30D, 1Ds, 550D and 5D. Much of my current glass is L lenses, almost all the rest are Sigma lenses. The cool thing about most digital cameras is the diopter adjustment. I appreciate that now that I’m older and need reading glasses. What looks in focus to me, the camera may disagree with and the camera has been proven to be correct.
For most lenses, you can fine tune auto-focus, which is a good thing if the camera/lens is focusing in front or behind where it should be focusing.
Some focus points work with vertical lines, others with horizontal lines and some with both. It is important to know which points do what, in your viewfinder, for best results.
When I was shooting with the FM10, someone handed me their camera and asked for a photo, that was a long time ago and I forget the make and model but I remember looking through the viewfinder and thinking, “Wow, is this ever bright!” It was much brighter than my viewfinder. I should dig out the FM10 and compare it to a 5D Mk III and fast lens. I’ll try to do that tomorrow.
Some people rotate the camera with their hands, others bend at the waist. Got a couple of cameras? Have your wife use one to make a movie of you while recomposing. It may be enlightening.