Aperture, often represented by the f-stop number, dictates the size of the lens opening. A lower f-stop number (like f/1.4 or f/2.8) signifies a wider opening, allowing more light to enter the camera. This wider opening also creates a shallower depth of field, meaning only a narrow plane of the image will be in sharp focus, while the foreground and background will be blurred (bokeh). Conversely, a higher f-stop number (like f/8, f/11, or f/16) indicates a smaller opening, restricting the amount of light. This narrower opening results in a larger depth of field, ensuring that more of the scene, from foreground to background, remains in sharp focus. This is particularly useful for landscapes or group portraits where you want everything to be clear.

Shutter speed refers to the duration for which the camera's sensor is exposed to light. It is typically expressed in seconds or fractions of a second. A fast shutter speed, such as 1/1000th of a second, will freeze action, making it ideal for capturing fast-moving subjects like athletes or birds in flight. This rapid exposure minimizes the chance of motion blur. On the other hand, a slow shutter speed, like 1 second or longer, allows more light to enter the camera and can be used to intentionally create motion blur, such as the silky effect of flowing water or light trails from moving vehicles. However, using slow shutter speeds requires a stable camera, often achieved with a tripod, to avoid camera shake.

ISO is a setting that dictates the sensitivity of your camera's image sensor to light. A lower ISO value, such as 100 or 200, means the sensor is less sensitive to light. This is the preferred setting in bright conditions as it yields the cleanest images with minimal digital noise or grain. As light levels decrease, you'll need to increase the ISO to achieve a proper exposure. Higher ISO values, like 800, 1600, or even 3200 and beyond, make the sensor more sensitive to light, enabling you to shoot in darker environments without underexposing your image. However, this increased sensitivity comes at a cost: higher ISO settings often introduce digital noise, which appears as speckles or graininess in the image, particularly in shadow areas, and can reduce overall image detail and color accuracy.