Shutter Speed and You

Now that you've practically mastered ISO and Aperture, we'll turn our attention to shutter speed - the last remaining setting in what some photogs call the "Triangle of Exposure." Your shutter speed is just that – the amount of time that your shutter is open. This is measured in seconds and can also be set manually by you or automatically by the camera, according to how long the shutter needs to be open in order to let in the necessary amount of light for a correct exposure.

Related terms and phrases: long or short exposures, seconds, exposure time

You'll find your shutter speed is adjusted with the small dial found by your shutter button when in Tv or Manual mode. (Some cameras offer a "bulb" mode which keeps the shutter open for customizable amounts of time.) The shutter of your DSLR is similar to your car engine in that it has a life span. Amateur and mid-range cameras have an approximate lifespan of about 50,000 shutter clicks while higher end professional grade DSLR's approximate 100,000 images.

The shutter speed is measured in seconds – most often the shutter is open for a fraction of a second. Only the denominator is displayed in your viewfinder. Long shutter speeds of whole seconds are displayed with second marks (4”). The larger the denominator (numbers again, hang in there), the faster the shutter speed. That means the shutter is open for a very short amount of time (i.e. 1/500 of a second), and therefore ample light is needed in order to make a correct exposure (that's where your aperture training comes in!).

If you're looking to capture a city skyline at night, you'll need to use a longer shutter speed (smaller denominator or even whole seconds). Keep in mind that the longer your shutter is open, the more important it is that your camera keep still. Most people recommend using a tripod when shooting 1/60s or slower. Image stabilization is being added to an increasing amount of lenses, allowing the user to shoot with a slower shutter speed and receive less camera shake. A rule of thumb regarding focal length and shutter speed: it's a good idea to keep the denominator of your s.s. larger than the focal length of your lens. (Shooting with a 200mm lens, keep shutter speed at least 1/250s. Lens with a fixed 50mm focal length should use at least 1/60s s.s.)

As with aperture, shutter speeds double in amount:

1/500s, 1/250s, 1/125s, 1/60s, 1/30s, 1/15s

The smaller the denominator number, the longer the shutter is open and the more light is allowed in. Adjusting your speed from 1/500s to 1/250s will double the amount of light exposing the film/hitting the sensor.

So what can shutter speed do for you? It all depends on what kind of movement you want to capture in your image. You have the power to freeze all movement, or to capture an image full of movement and blur.  A faster shutter speed freezes the movement; a slower shutter speed allows the movement to blur.

The images below were taken with a slow shutter speed. The shutter was open for 1/5s during the exposure and I followed the moving subject so that it was clear and the background became blurred. Had I remained still, the car would become the blurred motion.

F/29 at 1/5s

When your subject is stationary, you can also achieve motion blur by using a slow shutter speed as in the photo below.

F/22 at .3s

Because the shutter is open for an extended period of time, the aperture is quite small. The time of the exposure lets in enough light for the aperture to remain narrow. Need to freeze the movement? Then make sure your aperture is wide enough to let in enough light for correct exposure over a very brief amount of time.

These photos were taken last summer during a family vacation. My four younger cousins are water sport masters as evidenced by the mad air they're getting. I felt successful when I remained attached to my board...

Images 1&2 : F/4.5 at 1/2000s     Image 3 : F/4.5 at 1/2500s

So to bring it all together – ISO, Aperture and Shutter Speed are three adjustable elements that work together to create a correctly exposed image. Remember that you have the most control over these elements when shooting in Manual mode.  A few things to keep in mind:

A change in aperture or shutter speed requires a change in the other. Opening your aperture a bit wider? This will let in more light, allowing the shutter to be open for a shorter amount of time. Increasing one will allow you to decrease the other to make a correct exposure. (For example, if a correct exposure is a result of F/2.2 at 1/800s, a correct exposure will also result from F/1.4 at 1/1600. More light is allowed in with the second combination, so a quicker shutter speed is acceptable.)

Shooting in low light? Keep in mind that you can always increase your ISO, but watch out for that grain. Other low light options include opening your aperture wider to let in more light or increasing the length of time the shutter is open.

I suggest visiting this site if you want to learn more.

Upcoming LGP EDU : Lighting, Composition, Working with People....

Getting to know your ISO.

Welcome to the first installment of LGP EDU! Initially I considered doing one post about all things technical -- shutter speed, aperture and ISO -- but then that proved to be ridiculous. As a result, we'll start with ISO  and ease our way into the more involved techie subjects. Without further ado, let us get to know a little ISO.

ISO: the unit of measurement used to differentiate film speed – from the International Organization for Standardization. (Yes, I am aware that the O and S are switched. For this, I do not have an answer.)  The lower the ISO, the less sensitive the film is to light, therefore needing more of it (light), to make a correct exposure. This is why lower (100, 200 ISO), films are ideal for bright sunny days and portraits; the light is abundant, so a lower sensitivity film is acceptable.

Inversely, the higher ISO value, the more sensitive the film is to light. Larger number ISO films 600+ are ideal for low light situations or capturing fast action. The film's sensitivity allows the shutter to be open for shorter amounts of time, able to freeze fast action sports photos, for example.

ISO if often described by the amount of “grain” you see in the final product. Higher ISO speeds produce “grainier” photos. These grains that you see are the literal grains of silver halide that make up the films sensitivity to light. Each one of these grains develop individually.

On to the digital age: While individual manufacturers calculate their particular digital model's ISO settings, they are very similar to the calculations made for film.  High-end professional DSLR's offer ISO settings 6200 + higher with an impressively low amount of grain. If you don't have a high end DSLR, keep in mind that the higher the ISO you use, the lower the quality you'll receive in your final product (more grain).

DSLR cameras allow the user immensely more flexibility in regards to ISO. You can take 20 consecutive photos each with a different ISO setting. Let the same rules apply; when outside with abundant light, a lower ISO setting of 200 -400 is ideal for crisp photos and portraits. For family portraits, kids, and outdoor wedding portraits, I stay within this bracket. Lower light situations (wedding ceremonies, indoor shots), and fast motion photography should use a higher ISO 600+. ISO 100 is ideal for well-lit landscapes (which don't move).

Following are three examples of different ISO speeds. I've set the photos to B&W to best compare the amount of grain.

The above photo was taken in a very low lit hotel lobby in NYC (that's Ben and Woody Allen!). It is my personal preference to never use the pop up flash on my DSLR. I use an external Speedlight 580 for weddings and portraits, but when flash is not allowed (wedding ceremony), or available (impromptu celebrity encounter), I up the ISO and open wide the aperture.

ISO 800 f.1.2 at 1/125s

Ben needed an author photo for one of his publications so we used the natural morning light coming in from our windows and my reflector to bounce the light into some shadows on his face. Being indoors, a slightly higher ISO was required.

ISO 400 f.1.2 at 1/200s

This is Ruby- she's one of my favorite people. We did portraits at the Courtyard Retirement Home in Tennessee for 2010 Christmas presents. A make shift studio was set up outside with a white sheet and a reflector which provided ample light and allowed me to shoot at a lower ISO for a crisper image.

ISO 200 f.2.8 at 1/125s

Now what? When using your camera in Auto or Program mode, your DSLR will set the ISO according to the internal light meter. It can be set manually by selecting the ISO button (usually found on the camera body or within a menu). I suggest sitting down with your camera and photographing the same image repeatedly using a different ISO for each exposure for a first hand ISO experience.

Congratulations - you have made it through LGP EDU Installment One! I know it's techie; I promise more excitement is to come! Please join the conversation - feel free to post comments, questions or helpful links below!