Equivalent Exposure
Cindy, Ernie and I went to the East – West Center on Presidents day to do an Equivalent Exposure shoot. This is to show you how you can change either the aperture or shutter speed and still capture the photo in the manner you want as your original. If you adjust the shutter speed to a faster speed you need to make the aperture smaller. Another example is if you change the aperture to a smaller aperture you need to make the shutter speed slower.
Here is a practical example of how it is best used. You take a photo in Program mode and you like the exposure but the background is too in focus. You want to blur the background some to what do you do. Well you check to see the setting of the original photo to find out that the photo settings were 1/60 sec, at f/16. You want to blur the background some so you may want to use an aperture of f/4 so what is the equivalent shutter speed? Well between f/16 and f/4 is four (4) steps wider (f/16 to f/11, f/11 to f/8, f/8 to f/5.6 and f/5.6 to f4 ) so you need to adjust the shutter speed three (steps) faster. Well 1/60 sec. to 1/125 is one step, 1/125 to 1/250 is the second step , 1/250 to 1/500 is the third step, and 1/1000 is the fourth step. Therefore you equivalent exposure is 1/1000 sec. at f/4.
Aperture steps:
f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22
Shutter speed steps:
15, 30, 60, 125, 250, 500, 1000
By the Way, most digital SLR cameras have two settings for the number of between stops on your camera. Most have 3-clicks and 2-clicks, which mean that between each full step is either three (3) or two (2) clicks. So between f/4 and f/8 there are three or two clicks to go from f/4 to f/8.
Here is one set of examples:
