Vintage Camera ISO
100 - Full Sun, no shade.
200 - Lots of sun, could be in partial shade or an overcast day out in the open.
200 - Inside on a sunny day, directly by a large window.
400 - In the shade on a sunny day or under a covered area on an overcast day.
700 - Inside on a sunny or overcast day (near a window)
640-800 - Sun is starting to set and less light.
800 - Inside, quite a distance from a window (sunny outside)
850-1000 - Inside, quite a distance from a window (overcast day)
1250 - Inside during the evening, light bulbs are the only source of light.
1600 - Inside a dark room where there is a light source (theatre, school production, etc)