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To get the most from your X100S now, you need to understand the principles of expo-sure. Without this basic understanding, it may be difficult to move forward and improve your photography. It’s easier to go from “snapshots” to “great shots” with a clear under-standing of the core photographic principles.

Exposure is the process whereby the light reflecting off a subject passes through the opening in the camera lens onto the sensor within the camera, for a certain period of time. Technically, this combination of the lens opening, the shutter speed selected, and the sensitivity of the sensor is known as the exposure value (EV), the sum of these compo-nents needed to properly expose a scene.

This relationship is often referred to as the “exposure triangle” and is made up of the following elements:

• ISO: This is the measurement that determines the camera sensor’s sensitivity level.

ISO stands for International Standards Organization, but the acronym itself is used to describe the level of sensitivity of the camera’s sensor to light. The higher the ISO, the less light is required to obtain a good exposure. Or, in reverse, the lower the light levels, the higher the ISO that is needed.

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• To achieve a proper exposure, the lens needs to adjust the aperture diaphragm to control the volume of light entering the camera. Then the shutter is opened for a relatively short period of time to allow the light to hit the sensor long enough for it to record the image.

• Standard ISO numbers for the X100S start at 200 and then double in sensitivity as you double the number. So ISO 400 is twice as sensitive as 200.

• Aperture: Essentially, aperture is the size of the lens opening when a photograph is taken. The size of the hole has a direct correlation to the amount of light that can get into the sensor. The larger the aperture size, the more light will fall on the sensor; the smaller the aperture size, the less light will fall on the sensor. The X100S’s aperture range is f/2 through f/16. Generally speaking, a lower f-stop number will allow you to shoot in lower light, and will usually offer more depth of field and bokeh depending on the subject and the framing.

• Shutter speed: The speed to which you set the shutter on the camera controls the amount of time the shutter remains open, which in turn determines how much light can hit the sensor. The shutter speeds available on the X100S range from 30 seconds to 1/4000 of a second. Normal shooting will see you working within a range of around 1/30 to 1/2000 of a second, but obviously this may change depending on the circum-stances of the shot you are taking at the time.

A change in any of these factors (ISO, aperture, or shutter speed) will require a reciprocal adjustment in one or both of the others. For example, if you let more light into the lens by choosing a larger aperture, you will need to shorten the time the shutter is open.

Conversely, if you increase the shutter opening time to allow more light, then you’ll need to decrease the aperture.

always Be prepared to Shoot

My camera goes everywhere with me. Because I’m always keeping an eye out for great photographic opportunities, it’s important to me that my camera is at the ready at all times. I rarely have the camera stored in a bag or under my coat, even in poor weather. Instead, I prefer to have the camera on a strap over my shoulder or in a hip holster. The lens cap is always off when I’m out shooting, so I’m ready to capture an image as soon as the opportunity arises. To be ready and able to focus my attention on shooting at all times, initially I set the ISO, aperture, and shutter speed—thus I’m not preoccupied with configuring my camera constantly.

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2 : F i r S t t h i n G S F i r S t 35 When you point your camera at a scene, the light reflecting off your subject enters the

lens and is allowed to pass through the sensor for a period of time dictated by the shut-ter speed. The amount and duration of the light needed for a proper exposure depends on how much light is being reflected and how sensitive the sensor is. To work it out, your camera utilizes a built-in light meter that looks through the lens and measures the amount of light. That level is then calculated against the sensitivity of the ISO setting and an EV is established.

What’s a Stop?

The term stop is used a lot in the photography world. It refers to the f-stop, which is the term used to describe the aperture opening of the lens. When you need to increase your exposure, you might refer to “adding a stop.” This is not specific to just aperture, however; it can also relate to ISO and shutter speed. So when your image is too light or too dark, or you have too much motion in the scene, you will likely change things by moving a “stop” or more.

There are many ways to achieve a perfect exposure, because the f-stop and the shutter speed can be combined in different ways to allow the same amount of exposure. The following table shows a list of reciprocal settings that would all produce the same expo-sure. This means that any of these settings would each result in the same amount of light hitting the camera’s sensor to make the exposure.

Reciprocal Exposures at ISO 100

Aperture (F-Stop) 2.8 4 5.6 8 11 16 22

Shutter Speed 1/1600 1/800 1/400 1/200 1/100 1/50 1/25

Note that each time we cut the f-stop in half, we reciprocate by doubling the shutter speed.

Now we can start using this newfound knowledge and information to make educated choices with respect to shutter speed and f-stop. Let’s bring the third element into this by changing our ISO by one stop (doubling it) from 100 to 200.

Reciprocal Exposures at ISO 200

Aperture (F-Stop) 2.8 4 5.6 8 11 16 22

Shutter Speed 1/3200 1/1600 1/800 1/400 1/200 1/100 1/50

You can see that as we have doubled the sensitivity of the sensor (ISO), we now need half as much exposure as before to achieve the same result.

ptg13805176 You may be asking, why not just use the exposure setting of f/16 at 1/100 second? Why

bother with all the reciprocal values when this setting clearly gives us an established and accurate exposure? The answer is that the f-stop and shutter speed also control two other important aspects of the image: motion and depth of field.

Sunny 16

There is a commonly quoted rule in photography called the “Sunny 16 Rule.” The idea is that on a bright sunny day with no cloud cover, you will obtain the correct exposure by setting your aperture to f/16 and your shutter speed to the same amount as your ISO. For example, if your ISO is 200, the proper exposure would be f/16 at 1/200 second. If your ISO is 400, the exposure would be f/16 at 1/400 of a second.