rajfotografie

Aperture

What kids do for fun—peeking through a small hole—is exactly how a camera works. The lens opening, or aperture, determines what the camera sees and how much light reaches the sensor.

Just like the girl shaping a circle with her fingers, a camera uses a set of overlapping metal blades—called aperture blades—to create an adjustable opening in the lens.

F-numbers

Aperture is expressed as an f-number (f/). A wide-open aperture has a low value, such as f/1.2, while a small opening has a higher number, like f/16. It may seem counterintuitive: a higher number means a smaller opening, and a lower number means a larger one—but that’s simply how the system is defined.

Aperture and light

The sequence of f-numbers (from 1 to 64) represents steps where each value lets in half as much light as the previous one. In photography, these steps are called “stops.” Moving to a higher f-number reduces the light; moving lower doubles it. It’s all about the surface area of the opening.

Aperture Values
1	1.2	1.4	2.8	4	5.6	8	11	16	22	32	64

Each step is calculated by multiplying the previous value by approximately 1.41 (the square root of 2). This ensures that each step halves or doubles the amount of light entering the lens.

Shutter Speed

Aperture is only part of the exposure story. Shutter speed plays an equally important role, and the two always work together.

Shutter speed refers to how quickly the camera’s shutter opens and closes. There’s no strict line between “fast” and “slow”—it all depends on your subject and creative intent.

Fast = less light

A fast shutter speed lets in less light. For example, at 1/8000 second far less light reaches the sensor than at 1/100 second.

The longer the shutter stays open, the more light is captured.

Slow = more light

Slower shutter speeds—like 1/60, 1/25, or even several seconds—allow much more light in but increase the risk of motion blur. In very low-light situations, exposures of over a minute are even possible.

Both fast and slow shutter speeds have their purpose. You choose based on what you want to achieve—whether it’s freezing action or creating motion effects.

Shutter speed isn’t just about avoiding blur; it’s also a powerful creative tool.

Proper exposure

Shutter speed also directly affects exposure. Too fast, and your image may be underexposed. Too slow, and it can become overexposed. Fortunately, built-in light meters help you find the right balance.

ISO Sensitivity

Sometimes, even with the right aperture and shutter speed, there simply isn’t enough light. That’s where ISO comes in—allowing you to adjust the sensor’s sensitivity to light.

ISO standard

ISO values are based on international standards and indicate how sensitive your camera sensor is. A higher ISO means greater sensitivity, allowing you to shoot in darker conditions. Modern cameras typically range from ISO 50 to well over 100,000.

High ISO

While higher ISO settings are useful in low light, they come with a trade-off: increased image noise. Many photographers prefer to stay below ISO 6400 for optimal image quality.

Noise and creativity

Noise isn’t always a drawback. Some photographers intentionally use high ISO values to add grain and character to their images, enhancing a specific mood or style.

From film to digital

In the days of film photography, ISO was known as ASA. Faster films (like ASA 400) were more light-sensitive but also produced more grain—just like high ISO in digital photography today.