Ok, I think I am getting close, please correct me if I am wrong. thanks!
I have my A6 setting on AF39. Using AF-A but not in Auto or 3D, I manually select the focus point with the multi-selector. This lets me select any of the 39 points for my focus. Now, pushing the AF button, I can also select 1,9,21 or 39. This is the AF area "size" of the focus area and moving the point around moves this group around the matrix of the 39 points which I have set in A6.
>I'm not sure, but I think you are confusing two different >things: > >1) The AF-Area mode, which is set via the AF button on the >front of the camera. This determines how many focus points are >used for focusing. Since you aren't using Auto-area AF (or, >presumably, 3D-tracking AF), you are choosing whether to force >the camera to use only the AF point you select (Single-point >AF) or to also use points surrounding the AF point you select, >either 9, 21, or all 39 points. > >2) Number of focus points, set by Custom menu item a6. This is >poorly named in the manual. It would be better named number of >selectable focus points. All it does, when set to 11 >points, is restrict which focus points you can select with the >the multi selector. > >These two things are independent. That is, if you set a6 to >"AF11", you'll only be able to manually set one of >the 11 indicated focus points, but if you have one of the >Dynamic-area AF modes selected, the camera will still use the >surrounding AF points -- including ones you can't select >manually -- to dynamically focus. > >Note, too, that in a Dynamic-area AF mode, when you first push >the shutter button half way, the camera focuses using the >focus point you selected. Only if the AF system detects that >the subject has moved do the surrounding focus points come >into play. So, if you're testing in a situation where neither >the camera nor the subject moves (and have a good AF target >under the AF point), there isn't any significant difference >between Single-point AF and Dynamic-area AF. > >In all cases, the info screen shows which AF points may be >used by the camera once you press the shutter. In any non-auto >AF mode, the one you select is the primary one, and >autofocusing starts with that AF point. > >Hope that helps, and if I have misinterpreted the question, I >apologize. >