In this post we will discuss the Exposure triangle for beginners. This information is also very useful for experienced photographers alike. The exposure triangle represents a relationship among the three variable that define a correctly exposed image. These are ISO, aperture, and shutter speed. I have written separate posts defining the three variables individually.
As mentioned in earlier posts, good photography is achieved based on the three pillars of photography – ISO, Aperture, and Shutter Speed. Some photographers refer to this as the three Kings of photography. Every time you change any of these variables by one increment or decrement, you’re making a change by 1 stop or f/stop. For example if you change ISO from 100 to 200, that would be considered stepping up by 1 stop. Similarly, if you change aperture and shutter speed, you’re also changing it by an f/stop. F stop is simply a term used in photography to describe the change in any of these three variables.
Aperture, ISO, and Shutter Speed.
We will briefly recap the three prime variables in photography. Aperture is the size of opening of the lens which allows light to pass through and strike the surface of the image sensor thus producing an image. The aperture or the hole in the lens and the size of that hole can be controlled by the aperture settings.
ISO is the sensitivity to light of the image sensor. The sensitivity can also be controlled from the ISO settings. The lower the ISO setting (ie 100), the slower the sensor will react to light. Therefore, more light is required to produce an image. Higher the ISO setting (ie 400 and Up), the faster will the image sensor will react to light. Higher settings are useful in low light situations.
The Exposure Triangle (wiki commons)
And the final is variable the Shutter Speed. Shutter speed refers to the amount of time the shutter is held open for light to pass through. All this time the shutter is open, light keeps on flowing through the lens striking the image sensor to produce an image.
The exposure triangle is a guide that explains how a change in one variable will also need a change in another variable to produce a correctly exposed image.
For example, if you increment the aperture by 2 stops, then you would have to decrement, either the shutter speed or ISO by 2 stops.
Cameras set in auto mode do all the work for you. The camera will automatically select the aperture, ISO, and shutter speed based on the lighting conditions. Examples of these cameras include, point and shoot, mobile device camera, and also DSLR cameras set to auto mode.
Few examples to get the ball rolling
Say you want to take a picture outdoors on a sunny day. You want your picture to be nice and bright but not overly exposed so it looks like a white board. Also, the picture should not have motion blur to it. And you want your photo to be clean of any noise or grain.
For this scenario we will look at our exposure triangle and make adjustment to our ISO, aperture, and shutter speed.
Since I’m shooting outdoors on a bright sunny day, I have abundance of light available. So my ISO needs be somewhere around 100 to 200.
I don’t want any motion blur, so my shutter speed can be anywhere from 125 to 250. I also want my image to be sharp, then I would select my aperture to be around f/5.6 to f/11. The exposure Triangle gives this general guideline to shoot my photo based on my preferences.
In another scenario, the photo shoot is indoors and night. The lighting is not so great. We’ll use childrens’ birthday party for an example. We want our photo to be nice and clean but not have a frozen look to it. Since it is a birthday party, we want some sense of livelihood to our photo.
Again we would consult our exposure triangle and see what settings would give us the desired result.
Being indoor with poor lighting, we will set our ISO to 400 or 800. This is generally acceptable in low light situations. Our shutter speed could be around 60 – 125. This will give the photo some sense of motion. Although the sense of motion will be subliminal, but it will not give the photo a frozen in time look. To add more soft effect, we will choose our aperture value to be around 4 to 5.6. This will create a mellow background.
Hope these few examples will clarify how to use the exposure triangle chart.
Photography is an art and the setting you choose will be based on you intended artistic desire. There are hundreds of combinations of ISO, shutter speed, and aperture. Just like a juggler, it takes judgment and coordination. The best way to learn is by practice and experiment. The beauty of DSLR cameras is that you can take as many photos you like, without having to worry about the cost of developing film. Photography in film days was very expensive. Every shot the photographer took was final. There was no instant reproduction or going back. So get your DSLR camera our and start taking photos.
I hope this article has given you some insight on how to manually set your DSLR camera and get the desired results. If you have any questions or comments, please post them below.