Sony has released a7SII firmware update FW 1.10 designed to eliminate the occurrence of a black spot that may occur in a high intensity lighting part of a shooting scene such as sunspots.
Note: This condition is especially seen in PAL 25p, it rarely happens in NTSC 30p or 60p.
Mac OS X versions 10.7 – 10.11
Windows 10, 8, 8.1, 7 (with Service Pack 1), Vista (with Service Pack 2)
Before Updating Please Read:
Bulletproof Guide to Sony Camera Firmware Updates