The Weston Ranger 9 from 1966 was a departure from the Weston formula. It used a Cds cell instead of selenium for greater sensitivity and had a very narrow measurement angle. This meter has a viewfinder, similar to those found on cameras. You look through the viewfinder to determine the area being read.It was a favourite of Ansel Adams who found it perfect for his Zone system of exposure/developing/printing - a system infinitely boring but it worked for him. There was also a special zone system dial that could be purchased. It's completely dependent on battery voltage, and won't read correctly at anything other than 2.70 volts (two 1.35 cells, or the single stacked version) .
The PX13 batteries are no longer made however B&H can supply an Exell Battery 1.35V MRB625 Zinc Air Battery which is a replacement for the PX13 - see their website.
Here are some of the features listed in the booklet: Interchangeable calculators
Advanced sensitivity Million-to-one brightness range - 0.002 to 2000 candles per sq. ft.
Two light scales
Exposure dial Pointer lock on-off button
Either reflected or incident light measurements by using a converter)
ASA Film Speed Lock ASA can be set from 1.5 to 25,000
Shutter speeds can be set anywhere from 1/4000th of a second to 2 hours.
Lens aperture settings can be set between f/.5 and f/64
Battery check slider Battery compartment easily opened with a coin Uses one type PX 14 or two PX 13 batteries