Many people have report the sensor of the viewfinder (EVF) has a problem with Sony A7 generator 1 and 2. “If you want to use its LCD finder on the back, and hold the camera down at waist level, which in many cases shades the camera’s eyepiece sensor heavily, the sensor within the EVF’s rubber hood thinks the camera is being held to your eye and turns the LCD completely off in favor of the EVF only”.
Resolution 1: Clean the the sensor of the viewfinder.
Resolution 2: Customize a key to disable auto-toggle between monitor and EVF by going to:
“MENU > Gear > Finder/Monitor” and set it to “Monitor (Manual)”.
Resolution 3: Quoted: “
I finally discovered a simple fix to remedy this very aggravating situation using a product called Light Dims, which are little inexpensive, stick-on pre-cot pieces of a neutral gray shading material actually made for putting over glaring, bright LED’s that are overly bright and irritate you at night or in dark places.
By simply cutting a 3mm X 5mm piece of this material and applying it over the left half of the EVF sensor window, the sensor functions perfectly and the LCD remains on even in very low light, plus the EVF still switches on again automatically when the camera is held up to your eye! This is an incredibly simple fix that many Sony a7 users have wrestled with for months and have hoped and hoped that Sony would correct via a firmware update! It seems to work for all the Sony a7 models including the a7, a7R, a7II and a7S. These little gadgets are available on Amazon (http://www.amazon.com/LightDims-Original-Strength%C2%AE-Minimal-Packaging/dp/B00CLVEQCO/ref=sr_1_1?ie=UTF8&qid=1428490110&sr=8-1&keywords=lightdims) or directly from the company at: www.lightdims.com”