Aperture, ISO, and shutter speed are the three pillars of photography. These three lay the foundational knowledge in order to get the most out of your camera equipment and show off your creativity for each exposure. This is blog post #3 on shutter speed. Here are the first two links on ISO and aperture if case you missed them.
Simply put, a camera shutter is a curtain in front of the camera sensor that stays closed until the camera fires. The button that fires the camera is called the “shutter button”, because it triggers the shutter to open and close. When the camera fires, the shutter opens (curtain pulls back) and fully exposes the camera sensor to the light that passes through the lens. After the sensor is done collecting the light, the shutter closes immediately (curtain closes) stopping the light from hitting the sensor.
Shutter speed, also known as exposure time, is the unit of measurement which determines how long the shutter remains open, or in other words, how long the camera's curtain is open to record the image. The slower the shutter speed, the longer the exposure time. Shutter speeds are measured in fractions of seconds, minutes or hours (normally you will see/use seconds). For example, shutter speeds could be 2 seconds, 1 seconds, 1/2 second, 1/4 second, 1/8 second, 1/15 second, 1/30 second, 1/60 second, 1/125 second, 1/250 second, 1/500 second, 1/1000 second, 1/2000 second, 1/4000 second, 1/8000 second, and so on. Each speed increment halves the amount of light entering the camera. In order to enable easier interaction between all pillars (ISO, shutter speed, and aperture), the shutter speed changes are graduated in one-stop increments. Every time the speed is doubled or halved, the change is one f-stop (one exposure value).
Shutter speed can be used to freeze a frame, or capture motion in a frame. If there is movement (people moving, flowers blowing in the wind, water cascading down a waterfall, tree leaves rustling) as you press the shutter button, a faster shutter speed will freeze the motion and make the image appear sharp and crisp. Often, faster shutter speeds (1/8000 s, 1/4000, 1/2000, etc.) are preferred to stop motion and capture it frozen in time, such as water droplets caught in mid air from a fountain. Since the shutter is opened so briefly, you can be confident in capturing hand-held images. As a side note, a wide aperture (lower f-stop number) is typically needed to allow enough light to enter the camera.
Slow shutter speeds, also known as long exposures, will cause the motion to blur, such as soft and smooth water in a stream. Since the shutter is often opened for a more than 1/8 of a second with these images, it will normally require a tripod in order for the areas in focus to remain sharp. Slow shutter speeds really allow you to illustrate motion and give a sense of the movement. In order to keep the shutter open longer, a smaller aperture (larger f-stop number) is typically used for these type of images. If conditions are still too bright to get the desired amount of blur, you can try to use a neutral density (ND) filter to slow the shutter speed even more. ND filters are like putting sunglasses on your lens, allowing less light to pass through the lens so the shutter remains open longer allowing for the blur to occur. Since less light is entering, the shutter speed is increased in order to properly expose the image. If your lighting is really dim, the slower shutter speed will allow more light into the sensor to properly expose the image (otherwise, the image will appear too dark.) Night photography of lighted city scapes are a great time to use long exposures.
Setting the Shutter Speed
Most cameras handle shutter speeds automatically through in-camera metering. When the camera is set to “Auto” mode, both shutter speed and aperture are automatically selected by the camera. When you shoot in “Aperture Priority” mode, you set the lens aperture, while the camera automatically sets the shutter speed. Personally, I shoot in Aperture Priority 90% of the time I use my camera. On a few occasions, I will shift to Shutter Priority mode, such as for times when creatively I desire a specific shutter speed to capture just the right amount of motion.
There are two ways to manually set the shutter speed:
Aperture, Shutter Speed, and ISO are all fairly simple on their own; however, they can become quite complex when you are out in the field and trying create a specific image. Not to mention that the only control you have over lighting conditions in the outdoors is normally to simply sit and wait for the light conditions to change. But that’s where the fun starts! Tinkering back and forth between different apertures, shutter speeds, and ISO values give you a lot of flexibility to be artistic. Experimenting in Shutter Priority mode is a good place to start if you are new to photography because I feel that the shutter speed concept is easier to grasp than aperture. Happy Shooting!
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