Exposure Light Meters     Rule of F-16     Infrared    Exposure Guide

They don’t/may not work to yeild proper exposure out of the box when purchased.
They need to be calibrated.
They may be off from the rule of f 16 exposure guide. (Use a gray card to verify)

All photometers are metering the exposure base on middle gray (works perfectly for color)

If you meter a white or black wall/card or it will come out gray.  Every been skiing on snow and pointed the camer down to get only gray snow.
Another problem, they all measure infrared light.

That’s great when you are shooting infrared film.

Husk, meters are set for exposure of color film/slides, a 7 zone scale.   B&W file has 10 to 11.  Hence that all weak gray look.
You don’t really need one.  You can get by without one.

The modification results in the meter ‘seeing’ the same as BW film, thus metering through filters for proper filter factors is possible and metering scenes with strong color accurately

Modified light meter (filter to not measure infrared light, calibrated, re-coated inside with extra black paint)

Worth It?
The Zone Systemznvicust
The Zone SystemSunny 16 rule – Wikipedia, the free encyclopedia     from the web