Hi. Please can someone help a newcomer to the world of custom buttons on the A7ii? I wanted to use back button focus and so disabled the shutter focus button and have set the AEL button to Focus On. That works fine - just what I wanted. However, when using Spot metering how do I lock that spot meter reading and then recompose my photo? Holding the customised AEL button doesn't do it and nor does the shutter button? I know I am missing something obvious but would appreciate some help. Thanks