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Understanding the Exposure Triangle: Shutter Speed, Aperture & ISO

From Amazon straight to your door, your new top-of-the-line DSLR has arrived. Now what? Shutter speed? Aperture? ISO!? What are these things? Can’t I just take a picture? Well you can, but if you want full, creative control of your photos then you need to know what the Exposure Triangle is all about! 

Shutter speed, or how long your camera makes that “clicky” noise. The clicky noise you hear when you take a photo, is actually your mirror flipping up, allowing light to be exposed onto your sensor. Most cameras can open and close the shutter as quick as 1/4000th but if you have a high-end DSLR, it can go to 1/8000th! You still may be asking, "what does these numbers even mean?".


The faster your camera can open and close the shutter, the more you’re going to freeze the action in your photo. If you are trying to photograph your kids soccer game, a shutter speed of around 1/250th or 1/500th of a second will do just fine! BUT if you’re photographing an F18 doing Mach 7, you’re going to want a shutter speed way faster than little Johnny's soccer game. On the other hand, if you’re photographing the stars, you’re going to want a longer shutter speed usually around 10 to 15 seconds!

A visual representation of shutter speed, aperture and ISO.
The Exposure Triangle

Aperture can be a little more confusing because it controls two things. Commonly referred to as “f” stops, aperture controls the amount of light that reaches the sensor. I like to think of aperture as the pupil in your eyeball. When you’re looking directly into light, it gets smaller. When you’re in the dark it gets bigger. Your cameras aperture blades do the same thing. Your aperture also controls your depth of field. The bigger the fstop, the less depth of field you will have. That’s a lesson for another day.  A wide open (f/2.8) aperture equals a brighter picture with a smaller depth of field. A small aperture (f/22) equals a darker picture and larger depth of field. 

ISO is basically a software in your camera that controls the sensitivity to light. A high ISO like 3200 will produce a much brighter picture than a low ISO of 100. Sounds all fine and dandy right? Well when you introduce more and more ISO to your image, you get what’s called noise. Noise is that grain you see in nighttime photos you take with your cell phone. It happens because your phone has internal ISO that it is boosting so you can see your subject in your photo. The benefit of raising your ISO is to get a higher shutter speed is dark situations, like a wedding or concert. 

So what do all three of these things have to do with each other? Well they make up what’s called the Exposure Triangle. If you shoot an image outside in sunny weather at f/2.8, you’re going to need a relatively high shutter speed to balance out all that light you’re letting hit your cameras sensor. On the other hand, if you’re shooting at f/22, you’re going to need a longer shutter speed to have a well-exposed photo. There may a situation where you will be letting in as much light (aperture) as you can while wanting to freeze motion but the ambient light isn’t bright enough. That’s where your ISO comes in. You pump that up to where it allows your shutter speed to be high enough to freeze the motion! 

The thing that really helped me learn the exposure triangle was practice. Shoot, shoot and then shoot some more. Shoot in your house, your backyard, ANYWHERE! Practice so when the time comes, that the light is perfectly golden and you have the best composition, you’re not fiddling with settings so much that you miss the shot. You know what you’re doing and what your settings should be. 

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