Modes! The first in a series of posts about Modes.
Aperture Priority, Shutter Speed Priority, Program and even the dreaded and much argued about Manual Modes seem to cause much confusion and anxiety when they all do essentially the same thing! So let go of the peer or self imposed pressure to use a mode recommended by this pro or that blogger.
There is no right or wrong 'Mode' to use. All the modes are making choices and trade-offs between ISO, aperture and shutter speed. You will soon realize you can use any mode in any situation to get the result you want so just use the one that makes the most sense to you.
An exposure is made up of three factors: shutter speed, aperture and ISO. Think of an exposure as drawing a bath, or running a bath in English. Shutter speed is equivalent to how long you leave the faucet open; the longer it's open the more water in the bath. Aperture equates to how far you open the faucet, and the wider it's open the more water you get. ISO may seem more esoteric, but effectively it is how big your bathtub is. A low ISO is a big tub needing a lot of water, and a higher ISO a smaller tub taking less water. As a result, a bigger tub is going to result in a higher quality bath than a smaller one!
The meter, which helps choose the aspects of the exposure we didn't set, is going to try and fill 'the tub' just under halfway every single exposure irrespective of what is in the scene. It doesn't know how deep we actually want the bath (how light or dark we want our picture). It is programmed to adjust our three variables so the right sized tub is just under half full.
All a mode allows us to do is tell the camera which option we want to set. How big the tub is (ISO), iso; how long to open the faucet (shutter speed) and how wide to open the faucet (aperture). If we use a mode to prioritize one or more of these criteria the camera will then assign the other values.
My next post will go a little deeper on modes and when one might make more sense than another. Later I'll introduce the concept of Exposure Compensation, EC, in our tub analogy that would be how deep or shallow we want our bath :-)
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