Question about stops regarding shutter and aperature

I always here people comment on how going from one f stop to higher one will reduce their exposure "x" amount of stops.I have heard the same in regards to shutter speed such as going from 1/250 to 1/100 persay will increase a given exposure by "x" amount of stops.

I shoot in manual all the time and only understand how to meter my shot according to the on camera meter.

But does anyone have reference to a chart or table where it would explain that moving from one aperature to another results in how many stops (and the same for shutter speed as well)? This would help in understanding how the meter moves according to my adjustments and what the meter is doing and where it is once it hits the edge and starts blinking...

Thanks

Setting shutter speeds by one whole "stop" are easy to figure out. Merely multiply or divide the current shutter speed by 2. One stop slower than 1/250 second, for example, is 1/125 second. That gives you twice the light for the exposure.

The math is a little more awkward for apertures, though. One "stop" is figured by multiplying or dividing the current f-stop number by 1.414. The conventional series of f-stop numbers for manually set lenses is 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, etc. Very few lenses for 35mm cameras (and current EOS cameras including digital types) can "stop down" beyond f/32, although you may find lenses for view cameras that can.

ISO settings - akin to the older "ASA" numbers for film - are easy to figure. Just like shutter speeds, multiply or divide the current setting by 2 for a one-stop change.

Just remember that a one stop change is always doubling or halving the exposure setting.

A website that explains things fairly well is the "Tedious Explanation of the F-Stop" or whatever it's called - www.uscoles.com/fstop.​htm

Exactly!

Thanks you rboth for your help.

Skip, I appreciate the explanation and will have to memorize those f stops...

Jim, looks like a good read. I appreciate the link.

Some help on what the settings are doing: Virtual Camera
Notice the background change when you use his "Shutter and Aperture" settings!


Need an exposure crutch?

More on how the subject affects the exposure in Post # 47

Frank, that is one of the best sites that I have seen for us neophytes.

One image = 1,000 words.