Developed by cinematographer Ed Lachman, ASC. the EL ZONE SYSTEM is an exposure tool based on stop values that relates one to one with lenses and light meters. EL Zone has 15 delineated zones in 1 stop increments plus + - ½ increments above and below 18% gray to for setting precise skin tones. Easy to use, 18% gray is gray, over exposure is white, under exposure is black. Each stop (zone) is a solid color making it easy to identify the stop value.
EL Zone shows an entire scenes exposure making light level adjustments easier.

Ed Lachman, ASC in Rec.709 on Panasonic VariCam 35

Ed in Panasonic VariCam V-Log

Ed Lachman with EL Zone on

Each stop of exposure is represented by a color. White shows areas of the scene that are over-exposed by 6 or more stops. 18% gray is normal-neutral.  Black is under-exposed by 6 or more stops. You can correlate the rest of the stops and their corresponding colors by remembering the acronym in a rainbow: ROY G BIV. (Red, orange, yellow, green, blue, indigo and violet). Or, print out the strip above and tape it to your monitor or EVF.

Over exposed. The sky is +4. Only a few windows are 18% gray.                               VariCam LT feeding an AJA U-Tap SDI to Quicktime screengrab.

Normal exposure. The sky is +2. Buildings are 18% gray or darker.                                                                   4 Normal.                                        

Under exposed. The sky is 18% gray. Everything else is darker. Day for dusk.                                                         6 Over.