Focus and recompose
Are we to guess which camera you're using, or do we just assume everything on this forum is about the 6D now anyway?
If it's the 5DIII or 1DX, then you just set your AF to Servo, your AF point selection to ALL. This way you start with the AF on the center point, and the camera tracks the subject laterally as you recompose, and it will reflect this in DPP.
If there's typos, you can be sure I used my iPhone.
|High Altitude Rocky Mountain Railroad by cjf2|
from On the Rails...
|Evening at the lake. by Murat ÜNSAL|