The Dreaded Exposure Triangle

Alright. So I (Kathy) am taking this as an opportunity to learn. Let me tell you, I can point and shoot all day long but when it comes to settings…I’m not the quickest at picking it up. Very often Matt stands over my shoulder explaining what goes where and when. He’s very patient like that. It seems I must learn to conquer…..


This post will be followed by three equally important posts as The Exposure Triangle is made up of three equally important parts:

  • Aperture – The size of the opening in the lens when a picture is taken.
  • Shutter Speed – The length of time the shutter stays open.
  • ISO – The camera sensors sensitivity to light.

There really isn’t an “ideal” or “perfect” exposure. That is purely personal taste. But, you can have bad exposure if it’s too bright or too dark. It’s all about learning to balance the three parts. The main lesson to take away from this triangle is that all sides are interconnected. If you increase/decrease the length of one side of the triangle you must equally increase/decrease one or both of the other sides if you want to maintain the same exposure. Make sense? Luckily, I was great at geometry and just having it put into triangle form helped me out. For those of you that still just don’t quite get it, I’ve found a few metaphors to explain the triangle: a garden hose, sun tanning, and a faucet filling a bucket. I’ve chosen to explain my favorite – a window.

Pretend with me that your camera is a window. This window has workable shutters that open and close whenever you want. On the inside of this window is a sheer drape, you know, to look good ‘n stuff.

Aperture (the size of the opening in the lens) is easily represented by the size of the window. If you have a giant ‘ol window, you’ll have a ton of freaking light. If you have a small hopper window, your house will be darker (I’m not sure why anyone would ever want a hopper window, but that’s neither here nor there). Now, relate this to your aperture: big = bright; small = dark.

Shutter Speed (the length of the time the lens stays open) is represented by the length of time you keep those shutters open each day. Leave the shutters open as long as it’s light out and your room will be lighter. If you close the shutters after an hour, your room will be darker. Now, relate this to your shutter speed: the longer it’s open, the brighter your picture will be.

ISO is the tricky one that doesn’t really fit the metaphor. I’ve seen it described as sunglasses and I think that’s just silly. I mean, who wears sunglasses at inside? I prefer to imagine ISO (the sensitivity of the sensor) as a fancy pants drape on the inside of your window. Lets pretend this drape has a few layers that can be adjusted to increase/decrease the light getting through (yeah, it’s all customizable, ’cause you’re rich in this fantasy). When the sun is rising in the morning you’ll want more drape layers covering the window because you have enough sunlight to light the room and don’t want to over-do it. When it’s getting dark out, you will want to pull back all of the drapes in order to allow as much of the available remaining light inside. Relate this to your ISO – In a situation where it’s dark, you’ll want to have a higher ISO to increase the sensitivity to light. In situations where it’s bright out, you can scale the ISO back because you already have an adequate amout of light.

Using this window, we find ourselves with many ways to increase the presence of light in the room. You could make the window bigger, leave the shutters open longer or have a fewer layers of sheer drape covering the window on the inside. On the opposite side, you can just as easily make it darker by making the window smaller, closing the shutters faster or have more layers of sheer drape covering the window to decrease the light.

Did that help? If not, it’s probably because I’m terrible at explaining things. Don’t worry, I made this a 4-parter for a reason.

Venture on to: A Little Thing Called Aperture for more info! :)


About Mathy Shoots People

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