Understanding-Exposure

History & Moonshots
When I was in my teens (in the mid-1960s) and just starting to make my way in the world of photography in a serious manner,Pentaxbrought out theSpotmatic. This was an SLR, very much in the modern idiom, but it contained the world's first behind the lens metering system. One had to manually close down the aperture to take a reading, and notwithstanding the name itwasn'ta spotmeter, but everyone who bought one thought that they'd died and gone to heaven. Imagine ‚a camera that could read exposure through the shooting lens, with filters, bellows extension and all. Damn, technology was advancing so much we might even land a man on the moon one day.
Tables, Charts and Selenium
Prior to this taking accurate exposure readings was problematic. There were, of course, clip on meters, hand-held meters, extinction meters (you're definitely over 50 if you remember these) and various exposure charts and tables. There was even that extremely esotericZone SystemfromAnsel Adam...