What is the recommendation for using the green "calibration" buttons on the MH-26 charger that comes with the D4? I have several EN-EL18's and wondered if I should be using this function and how often?
Is the BT-A10 compatible with the MH-26 or only the MH-26a?
I have both EN-EL4a and EN-EL18 batteries, and it would be nice to carry only one charger with the BT-A10 adapter when I travel. However, everything I see about the BT-A10 refers to the MH-26a and does not mention the MH-26. I'm not sure what the difference is between the two chargers.