Imagine stepping into a world where light is the key to unraveling breathtaking imagery. In this realm, ISO reigns supreme, shaping the sensitivity of the medium that captures moments frozen in time. But here’s the twist: ISO is not a one-size-fits-all concept. It morphs and adapts, taking on different roles in the realms of film and digital photography.

Let me take you on a journey through the intricacies of ISO, where we’ll delve into the nuances of its existence in both film and digital cameras. We’ll unravel the chemical secrets behind film ISO, where each roll holds a unique sensitivity to light, while simultaneously demystifying the digital counterpart, where ISO dictates the amount of light absorbed by the sensor to construct an image.

Together, we’ll explore the importance of ISO, peering into its profound impact on the quality of your photographs. As we navigate through this fascinating terrain, we’ll encounter the exposure triangle—a trinity formed by ISO, aperture, and shutter speed. It’s through their delicate interplay that we achieve the perfect balance of light, giving birth to images that dance with life and vibrancy.

So, whether you find yourself enchanted by the nostalgic embrace of film or immersed in the digital realm of limitless possibilities, join me as we unravel the mysteries of ISO and discover how it shapes the very essence of photography. Get ready to embark on a journey that unveils the power of light and its profound influence on the art of capturing moments that will stand the test of time.

Key Takeaways

  • ISO in film refers to the sensitivity of the light-sensitive emulsion layer on the film, while in digital cameras, it indicates the light sensitivity of the sensor (CCD or CMOS).
  • The ISO setting in digital cameras allows for versatility in adjusting the sensor’s light sensitivity.
  • Higher ISO settings increase the sensor’s sensitivity to light, but can introduce noise or grain in the photo.
  • Lower ISO settings produce darker photos with less noise, while higher ISO settings can help capture images in low-light conditions.
  • ISO is one of the three key elements in the exposure triangle, along with aperture and shutter speed.
  • Aperture controls the amount of light entering the camera lens, while shutter speed determines how long the lens stays open.
  • A faster shutter speed freezes motion, while a slower shutter speed creates motion blur.
  • Increasing ISO allows for working in low-light conditions, while lowering ISO is suitable for brighter environments.
  • Doubling the ISO results in a one-stop increase in exposure, while halving the ISO reduces the exposure by one stop.

What is ISO in film?

ISO in a film camera is not set at a push of a button. Instead, each film has a separate ISO rating which relates to the light-sensitive emulsion layer on the film. This rating can also be called film speed.

What is ISO in a digital camera?

In digital cameras, ISO speed is a number that indicates light sensitivity of the CCD or CMOS sensor. CCD or CMOS is a sensor technology, or the digital equivalent of film.

Why do digital cameras have ISO anyway?

The ISO setting in a digital camera is what makes it versatile. The lowest setting of ISO on a digital camera is usually 50, 100 or 200, while the highest setting is around 3200 or 6400, or even greater in some camera models.

When the ISO setting is low, the sensor is least sensitive to light. The sensor is more sensitive to light when the ISO setting is high. The ISO settings in a digital camera can be changed after every click if necessary. It gives an advantage to the digital cameras to be able to click correct exposed pictures even in low light.

When your ISO is at a higher level, you risk getting a lot of noise in your photo, but through digital cameras, you can keep the ISO a little lower and adjust the shutter speed and aperture to avoid the grain or noise. The manual settings on your digital camera allow you to choose the correct ISO as per your requirements.

How does ISO affect photo quality?

ISO will either brighten your photo or darken it. If your ISO number is high, the picture will be brighter and if your ISO number is low, your photos will be darker. Choosing the correct ISO can help you capture images in darker environments and lets you better adjust the aperture and shutter speed. However, selecting a high ISO could show a lot of grain in your photo, also known as noise.

Hence, you should increase your ISO only when you cannot brighten the picture with shutter speed, exposure, and aperture.

If you use a low ISO setting such as 300, your photo would be of a higher quality. For example, shooting outdoors under direct sunlight benefits from low ISO settings. Landscape photographers usually choose a lower ISO setting to make sure that the photos do not look over-exposed or grainy.

ISO comparison between 100 and 6400

The exposure triangle: ISO, shutter speed and aperture

Photography consists of 3 main elements – ISO, Shutter Speed and Aperture. Aperture is the depth of the field and the amount of light let on to the sensor or film, shutter speed is related to motion, and ISO is related to light sensitivity.

Whichever type of photography you do, these three elements are at the centre of every correct exposed photograph. There are many combinations of aperture, shutter speed and ISO that can be used to get the correct exposure. The combination you choose will reflect your artistic vision for a picture.


Aperture or F/stop controls how much light will go into your camera lens, which in turn will determine what your exposure will look like. It determines how wide your camera lens will open.

Shutter Speed

Shutter speed determines how long will the lens stay open to let a specific amount of light into the sensor. It is measured in fractions of seconds to multiple seconds for longer exposures.

A faster shutter speed will have the effect of freezing motion and a slower shutter speed will have the effect of blurring motion in a picture.


ISO determines how sensitive a photographic film emulsion or digital sensor is to light. An increase in ISO allows you to work even in low light and a lower ISO would be appropriate for brighter surroundings.

If you double the ISO it will result in a one-stop increase in exposure and halving the ISO means reducing the exposure by one stop.


As we reach the end of our exploration into the captivating world of ISO, we find ourselves standing at the crossroads where technical mastery meets artistic vision. ISO, a vital component of the exposure triangle, holds the power to transform the very fabric of your photographs.

Throughout our journey, we have witnessed the profound impact of ISO on photo quality. The delicate balance between light sensitivity and noise reduction guides us toward the path of perfection. By understanding the intricacies of ISO, we unlock the key to capturing images that radiate with clarity, detail, and emotion.

Whether we embrace the enchantment of film or embrace the boundless possibilities of digital photography, the quest for the perfectly exposed image unites us all. From the depths of a dimly lit scene to the dazzling brightness of a sunlit landscape, ISO guides us, shaping our perception of light and translating it into visual poetry.

Now, armed with this newfound knowledge, I invite you to embark on your own photographic odyssey. Experiment with ISO settings, push the boundaries of your creativity, and allow your images to tell stories that resonate with the souls of those who gaze upon them. Let ISO become your ally in capturing the fleeting moments that weave the tapestry of life.

Remember, it is not solely the technical aspects of ISO that make it captivating, but the boundless opportunities it presents for self-expression and storytelling. So, go forth, fellow adventurers, and wield the power of ISO to create images that transcend mere photographs. Unleash your vision, embrace the dance of light and shadow, and let your artistry shine through every pixel, every frame.

May the beauty and magic of ISO guide your photographic journey, forever igniting your passion for capturing the essence of the world around you. The stage is set, the curtain rises—what stories will you tell through the lens of ISO?