This handy little Black Cat Exposure Guide should be in every photographer's camera bag. No batteries required. It's just three pieces of paper held together with a rivet. It's the best thing I've seen to teach you to see light.

The instructions are pretty simple.
1. Move circular film speed dial until the scene letter matches the film speed.
2. Use triangular window to select any shutter speed and aperture.

The Black Cat Exposure Guide is a tri-fold. Inside are many different scenes with corresponding scene letters. Average scene, in full sun would be B. Cloudy, bright with no shadows, is D. Shade, under tree, is G.

If you are serious about photography then you should be serious about seeing light. This exposure guide is a wonderful aid in understanding just how much light there is. It's also a life saver if the light meter should stop measuring light. Not to mention that it gives bracket and zone information. There is even information on how to use it with pinhole cameras. But wait! There's more! There's also a gray card on the back.

This site explains it in more detail...

Exposure Guide

You can buy it here...

BLACK CAT Extended Range Exposure Guide