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What is ISO? Understanding ISO for Beginners

What is ISO? Understanding ISO for Beginners

Photography is a remarkable art form that allows us to freeze moments in time, capture beautiful landscapes, and tell compelling stories through visuals. As a beginner, diving into the world of photography can be an exciting journey filled with endless possibilities. However, it can also be overwhelming, especially when faced with the multitude of technical terms and settings to understand.

One of these crucial elements is ISO, a term that often leaves beginners scratching their heads. In our beginner's guide to ISO in photography, we'll unravel the mysteries of ISO, explain its significance, and help you harness its power to enhance your photographic skills.

Whether you're using a smartphone or a DSLR, grasping the concept of ISO will enable you to confidently manipulate light, adapt to various shooting conditions, and elevate the quality of your photographs. So, let's embark on this enlightening journey into the world of ISO, demystifying it step by step to empower your photography journey.

What Does ISO Stand For?

ISO in photography stands for "International Organization for Standardization." It is an international standard for measuring the sensitivity to light. In photography more specifically, ISO refers to the sensitivity of the camera's sensor or film to light, and it is a numerical value typically represented as an ISO number, such as ISO 100, ISO 200, ISO 400, etc.

What is ISO in Photography?

Put simply, ISO plays a crucial role in photography by influencing how the camera captures images in dynamic ranges and different lighting conditions.

What's the Difference between ISO, Shutter Speed, and Aperture?

ISO, shutter speed, and aperture are the three fundamental components of exposure in photography, each playing a unique role in how an image is captured. ISO, as previously stated, represents the sensitivity of the camera's sensor to light; with the higher number values representing an increase in light sensitivity while lower number values indicate a lower sensitivity.

Shutter speed determines the time the camera's sensor or film is exposed to light. A fast shutter speed, like 1/1000th of a second, freezes fast-moving subjects, while a slow shutter speed, like 1/30th of a second, captures motion blur.

action shot of track runners

The aperture controls the size of the lens opening, affecting the amount of light that enters. A wide aperture (e.g., f/1.8) allows more light and creates a shallow depth of field with a blurred background, while a narrow aperture (e.g., f/16) lets in less light and results in a greater depth of field with more focus. 

These three settings work together, and adjusting one necessitates compensatory changes in the others to maintain proper exposure and achieve the desired creative effect in digital photography.

What is the Difference between a High ISO and a Low ISO?

High ISO, typically represented by settings like ISO 800, 1600, or higher, increases the sensitivity of the camera's sensor to light. This is beneficial in low-light situations, as it allows you to capture brighter images without the need for slower shutter speeds or wider apertures. High ISO settings are valuable for night photography, indoor shooting, or freezing fast-moving subjects in low light. 

However, the trade-off is that high ISO settings can introduce digital noise or graininess into the image, reducing overall image quality. The extent of noise varies depending on the camera's quality and technology.

On the other hand, low, ISO values, such as ISO 100 or 200, indicate a lower sensitivity to light. This setting is preferred in well-lit conditions where natural or artificial light is abundant. Low ISO settings produce cleaner and sharper images with minimal noise, making them ideal for capturing landscapes, portraits, and situations where image quality is a priority. 

However, in low-light environments, using a low ISO may require longer shutter speeds or wider apertures to maintain proper exposure, which can introduce motion blur or affect depth of field.

In summary, the main difference between high and low ISO settings in photography is their impact on sensitivity to light and the trade-offs they entail. High ISO settings allow for better low-light performance but may introduce noise, while low ISO settings offer superior image quality but may require adjustments to shutter speed and aperture to maintain proper exposure.

Which ISO Setting Should I Use?

The ISO setting you should use when taking photos depends on various factors, including the lighting conditions, the desired image quality, and the creative effect you want to achieve. Here are some general guidelines to help you choose the appropriate ISO setting.

  • Low ISO (e.g., ISO 100 - 400):
        • Use low ISO settings when you have plenty of available light, such as outdoor scenes on a sunny day or well-lit indoor environments.
        • Low ISO settings provide the best image quality with minimal noise, making them suitable for landscapes, studio photography, and situations where image clarity is crucial.
        • When using a tripod or when long exposure times are acceptable, opt for the lowest native ISO setting (usually ISO 100) for optimal results.
  • Moderate ISO (e.g., ISO 400 - 800):
        • Choose moderate ISO settings when shooting in average indoor lighting or slightly dimmer outdoor conditions.
        • Moderate ISO settings strike a balance between image quality and the need to capture enough light. They are suitable for a wide range of photography, including portraits, travel, and events.
  • High ISO (e.g., ISO 800 - 3200+):
        • Use high ISO settings when you encounter low-light situations, such as indoor events, night photography, or dimly lit environments.
        • High ISO settings allow you to capture images with proper exposure in challenging lighting conditions, but they can introduce more noticeable noise.
        • When using high ISO settings, consider using noise reduction techniques during post-processing to improve image quality.
  • Auto ISO:
        • Many cameras offer an Auto ISO mode that automatically adjusts the ISO setting based on the available light and your chosen exposure settings (aperture and shutter speed). This can be convenient for quickly adapting to changing lighting conditions.
  • Creative Use of ISO:
      • Be bold and use ISO creatively. You can intentionally select a high ISO to introduce noise for artistic effect or to convey a certain mood in your photos.
      • Experiment with different ISO settings to see how they affect the texture and feel of your images.

    Ultimately, the choice of ISO setting should be based on your specific shooting conditions and creative goals. Consider the trade-offs between image quality and noise, and adjust your ISO accordingly to achieve the desired results while maintaining proper exposure.

    How to Change the ISO Settings on Your Camera

    To change the camera setting's ISO, you have to open your camera settings and find ISO settings. Some camera buttons may be specific. Once found, you may change the ISO by clicking either button (+ or - -). After finishing, press the menu button to make the change. Most camera models have auto ISO options which you can use if the picture doesn't show up. You may select the maximum range before adjusting shutter speeds and apertures. Cameras do it all.

    How to Adjust the ISO on Your Camera

    In adjusting the ISO of the camera, the instructions vary according to the model used by the camera. Almost all cameras have an automatic shutter button located above the shutter button. You can click on this button and rotate any knob or dial. You will see that your camera display or viewfinder changes your ISO. Other digital cameras may have dedicated settings in the upper body. The ISO adjustment can be made using this model simply by spinning it.

    ISO and Exposure: Using ISO the Right Way

    Using ISO effectively in photography involves understanding how it relates to exposure and image quality. Here are some best practices for using ISO:

    Start with the Lowest ISO Setting

    Whenever possible, begin with the lowest native ISO setting of your camera, typically ISO 100 or 200. This ensures the best image quality with minimal noise.

    Use Low ISO for Well-Lit Scenes

    an outdoor photo of a barn and lake

    Keep your ISO low in well-lit environments or when shooting outdoors during the day to maintain image clarity and vibrant colors. Adjust other settings like aperture and shutter speed to achieve proper exposure.

    Increase ISO in Low-Light Situations

    When faced with low-light conditions where maintaining a low ISO results in underexposed images or motion blur due to slow shutter speeds, gradually increase the ISO to achieve proper exposure. Find the balance between capturing a moving subject with enough light and minimizing noise.

    Use High ISO for Action Shots

    In situations requiring fast shutter speeds to freeze motion (e.g., sports or wildlife photography), most cameras don't hesitate to raise the ISO to maintain the necessary shutter speed, even if it introduces some noise.

    Consider Bracketing

    When capturing critical moments or scenes, consider bracketing your shots by taking multiple exposures at different ISO settings. This allows you to choose the best image later and helps manage potential noise.

    Leverage Noise Reduction

    Most modern cameras offer in-camera noise reduction features. Experiment with these settings to see if they help reduce noise while preserving image quality. Be cautious not to overdo noise reduction, as it can soften the image.

    Post-Processing Noise Reduction

    In post-processing software, you can apply noise reduction selectively to areas with the most noise while leaving the rest of the image intact. This provides more control over the final result.

    Shoot in RAW

    If your camera allows it, capture images in RAW format rather than JPEG. RAW files contain more data and provide greater flexibility for noise reduction and other adjustments during post-processing.

    Test Your Camera's Limits

    Get to know your camera's performance at different ISO settings and under various lighting conditions through experimentation. Understand when noise becomes too prominent for your specific camera model.

    Use Tripods and Stabilization

    When using low ISO settings in low-light situations, employ tripods or other stabilization methods to maintain image quality while avoiding camera shake due to slower shutter speeds.

    Adapt to the Creative Vision

    Remember that ISO can also be a creative tool. In some cases, you might intentionally use a high ISO setting to introduce noise for artistic effect, creating a vintage or grainy look.

    Best practices involve striking a balance between light sensitivity, proper exposure, and image quality, considering the limitations of your camera, and utilizing noise reduction techniques as needed.

    Understanding ISO and 'Noise'

    In photography, "noise" refers to the random and undesirable variations in brightness and color that appear as grainy or speckled patterns in an image. It is often compared to the grain seen in film photography. Noise can degrade the overall quality and clarity of a photograph, making it important for photographers to understand how it relates to ISO settings.

    The trade-off for increasing the ISO value is that it can introduce noise into the image, especially in areas with low light or dark shadows. This noise can manifest as random speckles or grain-like patterns, affecting the image's overall quality. Higher ISO settings amplify the sensor's electrical signals, including any electronic noise present in the sensor, which leads to increased noise in the final image.

    Photographers often strive to strike a balance between achieving proper exposure in low-light situations using higher ISO settings and minimizing noise to maintain image quality. Modern cameras and image processing software have improved noise reduction techniques, allowing photographers to mitigate the effects of noise to some extent. 

    Nevertheless, understanding the relationship between various ISO values and noise is crucial for making informed decisions about camera settings and achieving the correct exposure and desired image quality in various lighting conditions.

    Low vs High ISO Noise Visibility

    The difference between low and high ISO noise visibility in a photograph lies in how noticeable and pronounced the noise appears in the image.

    When you use a low ISO setting, such as ISO 100 or 200, the noise in the photograph is generally minimal and less visible. In well-lit conditions, low ISO settings produce images with high clarity, sharpness, and vibrant colors, as noise is barely noticeable or virtually absent. This makes low ISO ideal for situations where image quality is a priority, such as landscape photography or studio setups with controlled lighting.

    On the other hand, when you use a high ISO setting, such as ISO 800, 1600, or higher, noise becomes more visible and pronounced, particularly in areas of the image with low light or dark shadows. High ISO settings are necessary in low-light conditions to capture enough light for a properly exposed image, but they can introduce noise, which appears as grainy or speckled patterns. 

    The degree of noise visibility depends on factors like the camera's sensor technology and the quality of noise reduction algorithms. While modern cameras and software can help reduce noise, it may still be noticeable in images taken at high ISO settings.

    When to Use High ISO

    You should use a high ISO in photography when you encounter low-light situations where it's challenging to achieve proper exposure with a low ISO setting. Here are some examples of when to use a high ISO:

    Indoor Events

    The lighting may be dim when you're shooting indoor events like concerts, weddings, or parties. In such cases, using a high ISO allows you to capture well-exposed images without the need for slow shutter speeds that could result in motion blur. A high ISO helps freeze fast-moving subjects in low light.

    Night Photography

    a nightime photo of some lights

    For capturing scenes at night or astrophotography, high ISO settings are essential. They allow you to gather enough light to reveal details in the darkness, whether you're photographing cityscapes, stars, or the Milky Way.

    Sports Photography

    Sporting events often take place in stadiums or arenas with less-than-ideal lighting. High ISO settings enable you to maintain fast shutter speeds to freeze action while achieving proper exposure.

    Wildlife Photography

    a golden hour photo of a deer in tall grass

    In wildlife photography, you may encounter low-light conditions during dawn or dusk. A high ISO can be useful for ensuring that you can capture sharp and well-exposed shots of animals in these situations.

    Street Photography

    a photo of a night time tokyo street

    When you're photographing street scenes at night or in low-light urban environments, a high ISO helps you capture the ambiance and details of the scene without the need for a tripod or long exposure times.

    Emergency Situations

    In situations where you need to capture a moment quickly and don't have time to adjust other settings, a high ISO can be a lifesaver for getting the shot in challenging lighting conditions.

    It's important to note that while high ISO settings are valuable for low-light photography, they can introduce noise into your images. The noise depends on your camera's capabilities, so it's essential to balance the need for exposure with the desire for image quality.

    Additionally, modern cameras often have noise reduction features that can help mitigate noise to some extent. Experimenting with different maximum ISO settings and understanding your camera's performance in various lighting conditions will help you make the most of high ISO settings in photography.

    The Problem with High ISOs: Noise

    Noise affects high ISO settings more than low ISO settings primarily due to the way the camera's sensor operates at different sensitivities.

    At a high ISO setting, such as ISO 800, 1600, or beyond, the sensor becomes more sensitive to light. To achieve this increased light sensitivity, the sensor amplifies the electrical signals generated by the incoming light, including any electronic noise inherent to the sensor itself. This amplification process enhances not only the desired image information but also any random electrical fluctuations, which manifest as noise in the final image.

    In contrast, when using a low ISO setting, like ISO 100 or 200, the sensor operates with minimal amplification. This means that the signal-to-noise ratio is more favorable, as the desired image data significantly outweighs the electronic noise. Consequently, images captured at low ISO settings tend to exhibit minimal noise and maintain high clarity.

    Another factor contributing to increased noise at high and low ISOs is the need to capture more light in low-light conditions. To do so, the camera sensor may open its shutter for a longer duration or use wider apertures, which can introduce additional noise as a result of extended exposure times or the use of larger pixel areas to collect light

    In summary, high ISO settings lead to increased noise in photographs because they involve amplifying the sensor's electrical signals to compensate for low light. This amplification process not only enhances the desired image information but also magnifies any electronic noise, resulting in more noticeable noise in the final image. 

    When to Use Low ISO

    You should use a low ISO in photography when you have sufficient light and want to prioritize image quality. Here are some examples of when to use a low ISO:

    Daylight and Well-Lit Environments

    In bright daylight or well-lit outdoor scenes, using a low ISO setting like ISO 100 or 200 is ideal. This results in images with minimal noise and high clarity. It allows you to capture scenes with rich colors, sharp details, and excellent dynamic range.

    Landscape Photography

    Landscape photographers often prefer low ISO settings because they provide the best image quality. When shooting landscapes with a tripod and in good lighting conditions, using a low ISO helps capture every detail in the scene, from foreground to background.

    Studio Photography

    a portrait photo of a woman

    In controlled studio environments where you have full control over lighting, low ISO settings are the norm. The controlled lighting allows you to use low ISO settings to achieve the highest image quality without noise.

    Macro Photography

    macro photo of a dandelion

    When capturing close-up shots of small subjects, such as insects or flowers, using a low ISO is recommended. This ensures that the intricate details of your subject are preserved with minimal noise.

    Architectural Photography

    a photo of old Italian buildings and a cobblestone road

    When photographing buildings and architecture, especially during the day, low ISO settings are advantageous. They result in images with clean lines, sharp edges, and rich textures.

    Long Exposures

    When you want to create long-exposure images, such as silky waterfalls or light trails, using a low ISO is essential. This allows for longer shutter speeds without overexposing the image.

    Portraiture with Controlled Lighting

    In portrait photography, when you have control over lighting using artificial sources like strobes or softboxes, low ISO settings help capture skin tones and details with precision while keeping noise to a minimum.

    Low ISO settings are generally preferred when lighting conditions permit because they offer the best image quality. However, it's important to be aware that using low ISO may require slower shutter speeds and wider apertures to achieve proper exposure, so a tripod or other stabilization methods may be necessary in certain situations. Understanding when to use low ISO settings is key to achieving optimal results in photography.


    In conclusion, understanding ISO in photography is a fundamental step for beginners on their creative journey. It's not just a technical term; it's a powerful tool that empowers you to adapt to diverse lighting situations, expand your creative possibilities, and improve the overall quality of your images.

    By mastering ISO settings and learning how to strike the right balance between sensitivity and image quality, you'll gain greater control over your camera and produce stunning photographs that truly reflect your artistic vision.

    Remember that practice makes perfect, so don't hesitate to experiment with ISO settings and explore the incredible world of photography. With the knowledge you've gained from this beginner's guide, you're well on your way to capturing moments and telling stories through the lens with confidence and creativity. Happy shooting!