with ath's information, go to 'the ultimate exposure computer' by fred parker (google it) and get to the tables at the end that are the heart of the article. I use this inforation all the time on old camera with no or limited controls. I have old agfa's etc. that have only 1/30, 1/60, and 1/250 shutters. I type up the table contents in excel, and print them in small fonts, and then paste them on the back of some cameras. Then I draw diagonal lines across these speeds on the parker table, and I figure out exposure based on EV's in a very short time. After a while you start to look at outdoor lighting in terms of EV's, and then the next step is saying to your wife, ah, it's a beautiful f/8 morning outside.