View Full Version : Reciprocal Value F-Stop Chart

James Shadle
12-17-2009, 10:32 PM
Reciprocal Value F-Stop Chart

This chart helps visualize what needs to happen if you change the shutter speed or aperture and want the exposure to remain unchanged.

A full stop is either a halving or doubling of the amount of light reaching the image sensor or film.

An example could be that you want to freeze action in your photograph.

Your camera's shutter speed is 1/500 and your aperture is F8.
If you change the shutter speed to 1/1000 (twice as fast, allowing half as much light in) the aperture must be set to F5.6 (large aperture allows double the light as F8)

Going from 1/500 SS to 1/1000 SS the shutter speed doubles or is twice as fast, meaning half the amount of light will reaching the image sensor or film because the shutter remains open only half as long as before.

To preserve your current exposure value you will need to allow in twice the "volume" of light by going with a larger aperture(smaller F number), in this case a full stop.
By going from F8 to F5.6 you increase the size of the aperture (size of the lens opening that light travels through) allowing double the volume of light.

Jackie Schuknecht
12-18-2009, 12:40 PM
Thanks James, useful info.

Alfred Forns
12-18-2009, 01:22 PM
Lots of info there ... good reading !!! Thanks James !!!

Caspar Davis
12-18-2009, 08:06 PM
I've just been reading exposure in ABP1. This is a great complement to that.
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Sudhanshu Nafde
01-11-2010, 12:18 AM
Thanks a lot sir i was having the same confusion in my mind always, that how to make calculation between Aperture and SS for freezing the action..... I have ruined many of my opportunities due to confusion.... Now it is surely cleared.... and will try that out very soon....


Juan Carlos Vindas
05-02-2010, 09:09 PM
Thank you sir for your help and info.