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Monday, August 20, 2012

Photography 101 {What is the Exposure Triangle?}

Big stuff in the Photography 101 post today!
The exposure triangle is huge when trying to take great photographs.  Exposure will make or break a photo, and the exposure triangle is a large part of what photographers are thinking about when they take photos.  The exposure triangle explains how 3 factors work together to affect exposure.
I'm going to try and keep it as simple as possible, but there's a lot going on here.  So grab you camera, look at the buttons, and bare with me.

A lot of the time when I'm taking photos, someone will ask me, What buttons are you pushing?  Why did you move that dial and what direction?  or How do you know which button to push?  
Well much the "button pushing" that I'm doing while I'm taking photos has to do with getting a properly exposed photograph.

Let's start with a couple definitions-
  • Exposure - The amount of light used to take a photograph
  • Proper exposure - Capturing the correct amount of light when taking a photograph
We know that if there isn't enough light, the photograph will be too dark, or "underexposed."
If there is too much light, the photograph will be too light, or "overexposed."
As photographers, we're always trying to capture just the right amount of light to get the best exposure, and thus the best photograph.  
Proper exposure is a 3-way balancing act between 3 variables, ISO, aperture, and shutter speed.  If one factor shifts one way, one of the other two, or both have to compensate for the change in order to maintain a properly exposed photograph.  The 3 factors must stay in balance to achieve a good exposure.
  • ISO - How sensitive the camera is to light
  • Aperture - How wide the opening is that lets in the light
  • Shutter Speed - How long the opening stays open to let the light in 
A photographer that shoots in manual, controls all 3 of these variable.  
A photographer that shoots in auto-mode, controls none of these variables, and lets the camera automatically select all of them.  
A photographer that shoots in "aperture priority" (Av or A) controls only 1 of these variables, the aperture, and lets the camera automatically select the remaining variable(s) to achieve proper exposure.
A photographer that shoots in "time/shutter priority" (Tv or S) only controls 1 of these variables, the shutter speed, and lets the camera automatically select the remaining variable(s) to achieve proper exposure.  

ISO control how much or little grain (also called "noise") is in a photo.
Aperture/f-stop influences if a photo has a narrow vs. wide depth of field and thus influences if a photo has bokeh.
Shutter speed is manipulated to show motion blur vs. stopping action.
So how you choose to control these 3 variables, (ISO, aperture, and shutter speed) is up to you, depending on how you envision your image, how comfortable you are manipulating settings your camera.  And as long as you maintain the proper balance with the proper amount of light you will have good exposure.  

Let's say you have your camera set for a good exposure.  But you decide you want more bokeh in your photo so you select a wider aperture.  In order to maintain proper exposure, you must then decrease the amount of light (or you camera does it for you if you are in an auto mode) by selecting a faster shutter speed and/or increasing ISO.
Similarly, if you change shutter speed, (maybe you want to purposefully have blur or stop freeze some action) you must compensate by changing the aperture and/or ISO so that you still have the proper balance and proper exposure.

Keeping it simple, exposure is simply a 3-way balancing act between ISO, aperture, and shutter speed, to get the correct amount of light on to your photo and proper exposure.
Understanding the exposure triangle is one thing.  It's the first step.
Implementing it however is a whole different post that we can talk about later.

How you doing?  Does it make sense?

Photography 101


  1. This is a great post! You explained it VERY well! Your picture example is great too!

  2. Great explanation! I'm still trying to figure it out my camera settings though!!! :) Great tutorials!!

  3. As much as I enjoy using my mid-level (non-SLR) digital camera, you are really making me miss my old Nikkormat FT2! Thanks for a great series, I'm looking forward to lots more...

  4. I love these posts, Nancy! I have started taking photos in manual more often than not and have gotten a lot of lousy shots, but A FEW nice ones. And I begin to know what to do when they are lousy, so I consider that progress!

  5. I have just found your blog and went back over all your photography 101 posts and have learned a lot! Thank you so much for posting these.

  6. Saving for later, but thank you!! Look forward to reading in detail :)

  7. This was one of the best and easiest to understand explanations on the exposure triangle I've read so far! Thanks for sharing.


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