Light meters have never indicated EV (or if they claim to, they were mistakenly marked). EV is Exposure Value and relates to a combination of aperture f No. and shutter speed. LV or Light Value is exactly that, the Value of the level of Light.
Originally Posted by Diapositivo
Any meter marked up as EV is actually measuring LV
With ISO 100 film, the EV required is the same number as the LV measured.
I suspect that at one time, Mr Adams had a meter which only measured in foot candles so this system was perfectly workable for him. Now there is not much point as you have to use a meter either way so it might as well be what we now consider to be a normal photographic light meter.
EDIT: Just to take issue with myself. When I wrote "Light meters have never indicated EV" that was not 100% correct. A lightmeter can indicate which EV to set the camera to if it has a means of entering the ISO value but it does not give an EV level as a measure of light.