With digital cameras today, there’s almost never a need to “guess” or estimate exposure settings. Even so, you may eventually find yourself having to ignore your light meter and take the situation into your own hands. Or perhaps you’ll end up falling for film and buying an old camera without a light meter. Either way, having the ability to set exposure without the assistance of a meter is a good skill to acquire.
Since most cameras offer full stops, half stops, and third stops, you’ll need to have a handle on which ones are full stops so you can use the rule of reciprocals to change your f-number and shutter speed. Here’s a list of full f-stops.
f/1 – f/1.4 – f/2 – f/2.8 – f/4 – f/5.6 – f/8 – f/11 – f/16 – f/22 – f/32 – f/45
But you don’t need to memorize these numbers – there’s an easy little trick to them. You actually just need to remember two numbers: 1 and 1.4. These are the first two full stops in the list. Double them and you get the next two in the list. Double those and you get the next two numbers. Check it out:
1.0 – 2.0 – 4.0 – 8.0 – 16 – 32 – 1.4 – 2.8 – 5.6 – 11 – 22 – 45
You’ll notice that twice 5.6 isn’t exactly 11 and twice 22 isn’t 45. This is because the bigger numbers are rounded and the starting number isn’t exactly 1.4 – it’s 1.41421356… or the square root of 2.
Here are some additional resources having to do with Sunny 16 Rule and exposure.
The rule really works – if you don’t believe it, go try it out with any camera that has manual controls. I’ve been using the rule with my 1956 Minolta Autocord Twin Lens Reflex (no light meter) and it performs flawlessly.
Reposted from Epic Edits Weblog