My February focus was exposure, and I have to admit this one was a bit more of a challenge to practice than the Rule of Thirds, since there's a lot more involved. I had originally chose this as my challenge for February since I though it would be a basic one.
Exposure, or Exposure Value, as defined in
Wikipedia is the combination of the camera's shutter speed and realative aperature. The Exposure Value (EV) is also used to indicate an interval on the photographic exposure scale, with 1 EV corresponding to a standard power-of-2 exposure steps, commonly referred to as a stop.
The shutter speed (measured in seconds) plays an important role in that it determines the length of time the shutter is open, and can create interesting effects by blurring motion or halting motion at different levels. Most commonly seen in pictures of moving water, where a slow shutter speed blurs the moving water, and a fast shutter speed halts the movement of the water.
Each number represents seconds. For example, a scale that goes 2, 1, 1/2, 1/4 these are 2 seconds, 1 second, 1/2 second, 1/4 second.
The aperature (the
f number) determines how much light enters the camera. The larger the
f number the smaller the opening, the smaller the
f number the larger the opening. Therefore, larger numbers let in less light and smaller numbers let in more light. The aperature also effects the depth of field, but I'm going to leave that to look in to another month.
Each number represents one stop in the camera (
f-stop). For example, for a scale that goes 1, 1.4, 2, 2.8, from 1 to 1.4 is one
f-stop, and from 1 to 2 is 2
f-stops. Each stop is relative to the one before, so that 1.4 lets in half the light that was let in when the
f-stop was 1, or conversely 1 lets in twice as much light as 2 (because there's a stop in between, 1.4, which lets in one time as much light as 2).
Note that digital cameras can sometimes go up in 1/3 or 1/4 of a stop because they are more finely tuned that a traditional or older camera (just something to be aware of when adjusting the aperature).
Shutter speed and aperature have a direct relationship with each other. The smaller the aperature the faster the shutter speed, and the larger the aperature the slower the shutter speed. The camera will indicate when it is at an optimal setting by indicating a '0' rather than '+' or '-'. When a camera is in "Auto" it will always look for the '0'. If a picture is over-exposed the "whites" or highlights will be too bright, and if you under-expose the dark areas will be too dark. Both have the same effect - you loose the details.
I took a series of shots with the same subject to show the effect. I shot these with my camera in Shutter priority mode, which means I set the shutter speed and the camera chose the aperature setting for me.
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| Shutter speed - 1/2000, Aperature - F 6.3 |
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| Shutter speed - 1/8, Aperature - F 4.0 |
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| Shutter speed - 1", Aperature - F 8.0 |
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| Shutter speed - 4", Aperature - F 8.0 |
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| Shutter speed - 8", Aperature - F 8.0 |
My favourites would be the 1" and 1/8" shutter speed, and it's pretty close between the two of them. If I had to choose one it would be the 1/8" shutter speed with the F 4.0, simply because the railing in the background blurs a bit more and the angle is more sharply in focus.
What I learned about my camera - That on my camera when I look at the shutter speed, if it's red the image will be too dark or too light.
Even though I should focus on something totally different for the month of March I don't feel like I've worked with exposure enough. So, I'm going to spend my practice time using my camera in Shutter Priority, and take a few more experimental shots. I may move in to Aperature priority to work on Depth of Field, but we'll see what the month brings.