Shutter speed is the length of time that the shutter is open exposing the camera sensor to light. The faster the shutter speed is, the less light falls onto the sensor. If you slow the shutter speed down, there is more time for light to fall on the sensor and you end up with a brighter photograph.

Why don’t I shoot with a longer exposure all the time?

There are times when you will want to use a fast shutter speed, and there will be times when you will want to use a slower shutter speed. This all depends on the subject you are photographing.

When you shoot a photo with a slower shutter speed, the more likely it is to have the subject move or the camera shake creating a blur. This is fine if you are photographing something that is motionless such as a mountain. But not so much with a fast moving subject like sports or wildlife. You don’t want to photograph a Bald Eagle snatching a Salmon out of a river with a slow shutter speed. The eagle will just be a blur. You will want to use a fast shutter speed like 1/1000 shutter or 1/2000.

When to use a slow shutter speed.
(1/20 seconds to 30+ seconds. )

For motionless subjects like landscapes, you can slow your shutter speed down and not worry about motion in the picture. The mountain is probably not going to move. If you slow your shutter down too much such as 1/20 or 1/10 of a second while hand holding your camera, you could start to get blurry photos. Even when people try to hold completely still they still tremble a tiny amount, but its enough to get a blurry photo at a slow shutter speed. This is when you will need a tripod or monopod to hold the camera still. If your camera or lens is equipped with Image Stabilization, you can shoot with a slower shutter speed and still get sharp photos. Canon uses IS for image stabilization, and Nikon uses VR for Vibration Reduction. Even though they are called different things, they mean the exact same thing.

Hand holding your lenses allow you to stay nimble, but introduces the opportunity to introduce more camera shake into your photos. The focal length of your lens determines the slowest shutter speed you can shoot at. When you are shooting with a wide angle lens, because it is such a wide field of view, any movement you make with the lens will be so minuscule that it will be nearly unnoticed so you can slow the shutter speed even more. When you are shooting with a telephoto lens such as the 70-200mm. Any movement you make while zoomed will be incredibly noticeable, so you will need to shoot with a faster shutter speed. This is why a lower aperture is critical with longer focal length lenses.

If you are shooting photos in a dark location, you will want to use a slower shutter speed to let in as much light as you can. Opening up your aperture to  and increasing your ISO will also let in more light. You can also use off camera flash to add light to the situation to allow you to shoot at higher shutter speeds. If you ever attend a professional basketball or football game, you will sometimes see the entire stadium flash for a split second. It almost goes unnoticed unless you are watching for it. Those are the flashes triggering for the photographers along the sidelines. They use these to illuminate the entire arena and capture the action. If not for those flashes, the photographers reduce their ability to catch the action without increasing their ISO, lowering their aperture, or slowing their shutter speed. Those flashes allow the photographers to shoot fast and sharp.

There will be times when you will want to really slow the shutter down. you will want to use a longer shutter speed consisting of several seconds to photograph a waterfall and get silky smooth water. With a fast shutter speed, the water will be frozen in place. You want to use a slower shutter speed so the rushing water blurs as it falls giving the viewer a sense of motion. The same also goes for other subjects like moving cars, crashing waves, blowing grass, etc. Giving these subjects a slight blur will give the viewer a sense of motion.

Many digital cameras can set the shutter speed to as much as 30 seconds. When you use such a slow shutter speed, you are letting a lot of light into the camera and your photo can over expose quickly. When you over expose a photo, parts of the photo or the entire thing will be white. There is no details in a over exposed picture, and you will not be able to rescue it during post processing. To prevent over exposure, you can use a Neutral Density filter to let in less light. Think of sunglasses for your camera.

When to use a fast shutter speed.
(1/125, 1/250, 1/1000, 1/4000…)

If you are shooting sports of wildlife, you will want to use a faster shutter speed. When the football player scores the winning touchdown, you want to freeze the action to capture the look on his face, the ball crossing the line, the defense doing everything they can to stop him. Those things only happen for in instant and then they are gone. A fast shutter speed lets you capture those instances. With a slower shutter speed, it would all be a blur.

The higher you increase the shutter speed, the less and less light you are letting into the camera. If you ever try to use a fast shutter speed in low light, you will get an underexposed image. The image is now too dark because you are taking a photo at 1/250 of a second and not enough light is entering the camera. To counter this, you can open up the Aperture to increase how much light is let into the camera, or you can increase your cameras ISO to make the camera more sensitive to light. The higher the ISO is set, the more noise there will be in  your image. But sometimes it’s worth the extra noise to capture the moment. A noisy photo is better than no photo at all.

How does shutter speed work?

The camera shutter consists of 2 curtains. One that opens at the beginning of the exposure, and the 2nd curtain which closes at the end of the exposure. When you adjust the shutter speed, you are adjusting the amount of time between the first shutter opening, and the second shutter closing. As you increase the shutter speed, the more narrow the slit becomes between the opening and closing shutters.