There are 2 and only 2 requirements for EFCS. A menu entry (item d5) to set the EFCS to enable, and setting the Mup release mode. If these 2 settings are in place then 2 shutter release actions are required for an exposure and the EFCS will be used to start the exposure. Makes no difference if view ...

This is a real killer for using Helicon with the D810. I sold my D800 because I could not get rid of the effects of SHUTTER caused camera shake at higher magnifications. Note specifically SHUTTER and not MIRROR caused shake. The D810 does eliminate the problem with the EFCS (personally tested and ve...