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The Basics of Photography : A Quick Overview of Shutter Speed, Aperture and ISO

You just got your first DSLR camera. You take some pictures with the Auto Mode and wow, the pictures look amazing! But you don’t want to stop here, wishing to learn more about your camera, and photography in general. Then you have come to the right place. Oh, and you actually don’t need a DSLR. Any […]

You just got your first DSLR camera. You take some pictures with the Auto Mode and wow, the pictures look amazing! But you don’t want to stop here, wishing to learn more about your camera, and photography in general. Then you have come to the right place. Oh, and you actually don’t need a DSLR. Any mirrorless camera or point-and-shoot with manual controls will allow you to manipulate these settings.

In this article I will show you the 3 main settings in the manual mode of DSLR cameras: shutter speed, aperture, and ISO, and the effects each one has on the picture.

For more tutorial for beginner photographers, click here.

Shutter speed

The shutter speed determines how much time the sensor is exposed to light. Usually a fraction of a second (e. g. 1/250 aka 1/250th of a second), it represents the physical time your camera sensor opens to allow and record light. A shutter speed of 1 second literally means that your shutter opens up for one second to let light in the sensor.

A slower, faster, or shorter shutter speed (e. g. 1/4000th of a second) will let less light from entering the sensor, therefore decreasing the exposure of a picture (the image looks darker), while a slower, or longer shutter speed (e. g. 1/10th of a second) will let more light from entering the sensor, therefore increasing the exposure of a picture (making it look brighter). Let it too long and the picture will be white, and too short and the picture will be black.

A fast shutter speed will generally result in a sharper, frozen-in-time-effect. On the opposite side, a slower shutter speed will produce blurrier pictures (unless you have your camera set on a tripod). This can be used in creative effects such as in waterfalls or in long exposure nightscapes.

You will also need to adjust aperture or ISO consequently, in what we call the exposure triangle (subject to another article), in order to avoid over or underexposing a picture.

Big Wave
This was taken with a fast shutter speed: 1/200 of a second, which froze the water in the air.
Beach Rock
This picture, on the other hand, was taken with a much slower shutter speed: 4/5 of a second. As you can see, the water in the background looks a little silky.

Aperture

The aperture determine how much light enters in the camera through the lens. It is a measure of the lens’ focal (often physical) length divided by its aperture (opening of the lens) size, called the f/ratio. A 50mm lens with an opening diameter of 25mm will have a f/ratio of f/2, because 50/25 = 2.

A low, or fast aperture (e. g. f/1.4) means that more light will hit the sensor for the same unit of time (for the same shutter speed), while a high, or slow aperture (e. g. f/22) means that less light will hit the sensor for the same unit of time. An (imperfect) analogy on humans would be squinting your eyes (f/22) or opening them wide open (f/1.4).

One common mistake made by beginners is the confusion of a low aperture number (f/1.4) with a small opening hole (f/22). In fact, the smaller the f/ratio, the bigger the opening hole.

A large aperture (or lower f/number) will also have the property of having a shallower depth of field. Concretely, this means that a smaller part of the image will be in focus, and this effect is commonly used in macro photography and portrait photography. Meanwhile, a small aperture (or higher f/number) will have the property of having a deeper depth of field. This means that more elements of the picture will be in focus, which is excellent for taking landscape shots and archictecure, for example.

Close up leaf
The water droplet is in focus, whereas the background is very blurry. This was shot at f/5.6, which gives less depth of field.
Halifax
This picture was taken at f/11, which makes every part of the image very sharp: the water in the foreground, the buildings in the middle ground, and the clouds in the background.

The ISO is the sensitivity of the sensor to light. A smaller number (100-400) means darker images with very little noise. A bigger number (1600-6400) results in brighter images (useful in low light conditions) but with more noise. So you generally want to keep the ISO as low as possible.

With all this being said, you should take your camera and play around with it. You will have a better understanding of these 3 settings as you take more pictures. I will soon post a more in-depth tutorial, about recommended settings for different type of shots: portraits, waterfalls, stars, etc.

In the mean time, get out there and shoot!


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2 replies on “The Basics of Photography : A Quick Overview of Shutter Speed, Aperture and ISO”

Considering that this post approaches basic concepts, it contains, IMHO, several points that should be revised, as follow:
– different iris (aperture) settings give you brighter (or darker) images —>
this is true only if you lock the other settings. When you change aperture setting you change DOF (depth of field), the overall exposure will be defined also by other settings (i.e. ISO and exposure time)
– “less depth-of-field (every part of the image is sharp)” –> bigger F numbers gives you MORE DOF not LESS
– the “water droplet” picture –> f/5.6 is NOT an aperture giving you a lot of DOF (f/22 gives you a lot of DOF)

Somehow seems to me that aperture/DOF concepts explained in this article are the opposite of the real behaviour.

Hi Daniele,
The changes that each setting make is true if the other two are locked, just a you mentioned. I will be glad to clarify it.
Somehow I got mixed up with the DOF and aperture; it is now corrected.
Thanks for you comment!

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