Camera ISO Explained for Beginners

Michael • updated July 7, 2022 • 7 min read

Camera ISO Explained for Beginners. What is ISO in Photography?

The ISO setting is one of the three most important camera settings in photography. It can change the way how your photos look and even how they feel.

Image quality in photography is determined not only by exposure time and aperture but also by the ISO number, which is also part of the Exposure Triangle.

What is the ISO value, and how does it change the pictures you take? As a beginner photographer, it’s good that you’re learning about it. It’s a big step forward. In this article, we explain what ISO is and how you can use it to create better photos.

Camera ISO Explained for Beginners

The name “ISO” refers to International Standard Organization, and it is the standard classification for your camera’s sensor’s light sensitivity.

The camera sensor’s light sensitivity must be adjusted independently depending on the lighting situation.

The higher the light sensitivity and consequently the ISO rating for a photo shoot, the lower the lighting conditions are. As a result, the sensor’s sensitivity to light can be compared to that of a human eye.

When the light is turned off in the evening, it takes a while for the eyes to adjust to the new light conditions and recognize things.

The ISO number on the camera controls the camera’s response to the light environment.

Photo shows a dog catching a ball at Sunset, taken with a high Iso number
Dog catching ball, @Matthias_koll_leverkusen, Sony A7II, FE 24-70mm F2.8 GM, 70.0mm · ƒ/2.8 · 1/1000s · ISO 400

What is ISO in Photography?

“International Organization for Standardization” is abbreviated as “ISO.” The ISO of the camera, on the other hand, does not directly refer to this body, which develops technology and research standards.

There were two other standards in place before ISO: ASA and DIN. These were then integrated into the ISO standard in 1974.

Although the ISO standard was created to describe film speed, it was eventually adopted by digital camera manufacturers with the purpose of retaining film-like brightness levels. Since then, this norm has been applied to both photography and videography.

This photo shows a living room interior phototaken with a high ISO value
Interior photo with a high ISO, @Tama66, Nikon Z 6, 24.0-120.0 mm, 24.0mm · ƒ/5.6 · 1/800s · ISO 1000

The term “ISO” originally referred to a film’s sensitivity, or its capacity to “collect light.” The ISO value indicates how well a film can capture photos in low light.

The higher the ISO, the better. The fast film was referred to as high ISO film because it required a shorter exposure than low ISO film.

Using digital cameras has made life easier. In this case, the ISO value tells us how light-sensitive the image sensor really is.

The ISO values can be modified in the settings menu so that they are always in sync with the lighting conditions that exist at the time of capture.

In addition, a lot of digital cameras allow you to set the ISO automatically. The camera will constantly try to choose the best option for itself.

What Exactly is Base ISO in Photography?

Your “base ISO” is your camera’s lowest native ISO. This is a crucial setting since it allows you to achieve the best image quality while reducing the visibility of noise as much as achievable.

Graphic illustration use high ISO to brighten photos
Diagram, use high ISO to brighten photos

Many modern digital cameras have a base ISO of 100, however, some previous DSLRs and a few modern cameras have a base ISO of 200. As you can see. “base ISO” is the lowest ISO value a camera has to offer.

Ideally, you should take your pictures with the base ISO to get the best image quality. However, this is not always possible, especially in low light conditions.

ISO Value Table

Time of day and light situation ISO range examples:

  1. Very sunny daylight – base ISO 50
  2. Bright daylight, Normal daylight – low ISO 100 – 200
  3. Overcast sky, twilight – medium ISO 400 – 800
  4. Night or dark indoor – high ISO 1600 – 6400

Low ISO – Use with enough ambient light

As previously said, you should aim to use your camera’s lowest ISO (base ISO). Normally, this means ISO 50 or 100, but if there is a lot of ambient light, you can use a lower ISO to reduce the amount of noise.

Medium ISO – Use if the Ambient Llight is Insufficient

When your photos become too dark, gradually increase the ISO value until your image is bright enough.

You can still shoot without fear in the ISO range of 400- 800 because graininess appears mainly in the upper range of 800- 1600.

In sports photography, this ISO range is commonly utilized. To keep the subject sharp, you must shoot fast-moving subjects with an extremely quick shutter speed.

With a faster shutter speed, less light reaches the sensor. This is precisely where the ISO range comes in handy. So it can also be used when there is actually enough light, but at the same time, extremely fast shutter speeds are required.

High ISO – Use at Night or in dimly lit Areas

The human eye already detects less light at dusk. On full-frame cameras, very high ISO values allow you to go beyond these boundaries and photograph virtually in the dark (without flash or other light sources).

The sensor is adjusted to a very high ISO (for example, 51200) so that it can still pick up leftover light that is no longer visible to us. Infrared photography is similar.

example high ISO camera setting that creates grain
Comparison, high vs low ISO, high ISO increases noise level

However, such high ISO numbers should be approached with caution. The grain on your camera display will never look the same as it does on your home screen.

With cheap low-quality lenses, you won’t be able to shoot professional shots in dark settings. ISO will no longer be of assistance. Only a fast lens will allow you to go further with your photography.

Special High ISO and Low ISO

Advanced ISO settings are available on some cameras. The ISO values are referred to as “High ISO” and “Low ISO.” These are higher than the camera’s ISO range. The majority of the time, however, these just lighten or darken the photos captured by the camera.

As a result, the image loses quality. We would recommend, that you only use those settings when you know what you are doing.

Compensate Aperture & Shutter Speed with ISO

In fact, we’ve learned that low light needs a high ISO and low light needs a high ISO. This is mostly correct. But the shutter speed and aperture also affect how bright an image is, not just the ISO value. The exposure triangle in the below illustration shows this quickly.

Graphic Illustration Exposure Triangle in Photography
Exposure triangle

You can make an image brighter in three ways.

  • With a wide opening, like f/2.8. When the aperture is bigger, more light can get in, so the image is brighter. Depth of field is the second thing that the aperture does. The background becomes less clear as the aperture gets wider. Here, you can learn everything about aperture.
  • By making the shutter speed slower. If the shutter stays open for a longer time (for example, 1/50 second), light falls on the sensor for a longer time. You can see an example with a picture below.
  • By increasing the ISO value,

As you can see, there are many ways to get a bright picture, which means you can keep the ISO value low.

You can use a low ISO value even when it’s dark. For instance, if you put your camera on a tripod or a steady surface.

In this case, you can use a low ISO and make your photo brighter by taking it for a long time, since the tripod will keep the image from moving.

You can only use the camera up to a certain shutter speed before the picture gets blurry.

This photo shows a girl sitting in a park at a sunny day, photo taken with low ISO setting
Sunny day low ISO, @JillWellington, Canon EOS 5dIIi, EF50mm f/1.4 USM, ƒ/2.2, 1/1600s, ISO 100

Digital Camera Light Sensitivity: The ISO Range

Most current cameras have an ISO of 100 or 200 as a default. This standard value generates very low-noise photographs, therefore it’s preferable to use it as a starting point when adjusting the sensitivity.

One f-stop more or less light corresponds to doubling or halving the ISO value. Like all other exposure parameters, “ISO,” as it’s known among photographers, contains intermediate increments, commonly in thirds. As a result, your camera’s ISO range looks somewhat like this:

100 – 125 – 160 – 200 – 250 – 320 – 400 – 800 – 1600 – 3200 – 6400 – 12.800

The ISO value for 50 is sometimes known as “L” for “low,” as it is a lower, electronically generated value than the camera’s basic ISO.

The “high-ISO range” refers to ISO values above 6400, where image noise has already increased dramatically. For harsh illumination situations, both are usually more of an emergency solution.

auto-ISA camera setting display
Display ISO setting on DSLR

Image Noise – Disadvantage of High ISO Settings

You may believe that a high ISO number is an answer to all lighting issues. However, there is a catch. Increasing the ISO level has a drawback: the higher the number, the more likely noise effects will show in the photographs.

At ISO values of 400, in particular, inexpensive compact cameras frequently provide unsatisfactory pictures.

The basic noise of the picture sensors is the source of so-called image noise. The sensitivity of the image sensor is increased by increasing the ISO values. The noise level, on the other hand, rises at the same time.

The greater the value, the more noticeable the noise in the form of color and brightness noise gets on the photographs. These white or colored missing pixels are most noticeable in the photographs’ dark sections.

Image shows portrait women with ocean backdrop taken at low ISO

If your photos have picked up noise, you can use special software to partially repair the problem. After that, you can alter the raw data types with paid tools like Photo Ninja or Neat Image. It will never be feasible to totally remove errors, though. Your camera must be capable of delivering RAW files for this to work.

Auto-ISO Setting

First of all, let’s start with the basics: the overall exposure of an image is made up of the three factors mentioned above. You have the greatest creative possibilities with the aperture – it regulates the depth of field and bokeh, i.e. decides how much or little of the background you want to show in your pictures.

The exposure time factor (also called shutter speed) is quite self-explanatory: it indicates how long light falls on the sensor.

Here, optical differences often only arise at very long exposure times, where blurred or out-of-focus results can occur – the desired effect when photographing flowing water, for example.

Light sensitivity, on the other hand, usually has a negligible effect on the final image look: it is often only adjusted when the desired exposure can no longer be achieved via aperture and exposure time.

Image shows a decorated table taken at ISO 1000 with a lot of noise
Decorated table high ISO & noise, qkaboompics, Canon EOS 6D, 85mm, ƒ/1.4, 1/250s, ISO 1600

A higher ISO value lets more light into the picture and thus enables photography in darker environments – but also causes an increase in image noise.

Most cameras have an Auto ISO setting that usually works well in low light conditions. This setting has the advantage of allowing you to set the maximum ISO value you want to use.

The camera will then not pass that limit. Beginner photographers should set the Maximum ISO to 800, if you have an actual camera model ISO then 1600 is fine.

The disadvantage is that after the camera approaches this ISO level, it will use increasingly slower shutter rates. As a result, there may be more motion blur. So everything is a compromise, and you really should always examine your photographs on the LCD.

ISO in Analog Photography

  • ISO in the analog conventional photo sense is the measure for the light sensitivity of a film.
  • At that time, the technical standard for color films was initially ISO 50, later ISO 100, and nowadays ISO 200. The technical development brought better and better films to light.
  • Parallel to the light sensitivity, a second value moved, which was very important, especially for more ambitious photo fans and logically still is today: the film grain.
  • Without going too deeply into the technology, or even better into the chemistry, it is sufficient to know that higher light sensitivity is always accompanied by a coarser grain of the film.
  • The crystals on such a film become larger and coarser if they are to capture more light. Likewise, the brilliance of the photos decreases as the sensitivity increases.



Frequently asked Questions

Why is Camera Exposure Important?

Camera exposure is crucial in photography because it determines the brightness or darkness of an image. Proper exposure ensures that your subject is well-lit, colors are accurate, and details are preserved. It plays a vital role in capturing the desired mood and conveying your intended message through the photograph.

What is Exposure?

Exposure in photography refers to the amount of light that reaches the camera sensor or film. It is controlled by three fundamental elements: aperture, shutter speed, and ISO. These three factors work together to regulate the amount of light captured by the camera, ultimately determining the overall brightness and quality of the image.

What is Correct Exposure in Photography?

Correct exposure in photography refers to achieving a well-balanced image with optimal brightness and detail. It occurs when the camera sensor captures just the right amount of light to accurately represent the scene or subject. Correct exposure ensures that neither the highlights (brightest parts) nor the shadows (darkest parts) are overly blown out or underexposed, resulting in a visually pleasing and properly exposed photograph.

Why is Exposure Important in Photography?

Exposure is essential in photography for several reasons:
  • Image Quality: Proper exposure helps maintain image quality by ensuring accurate colors, preserving details, and minimizing noise or graininess in the final photograph.
  • Subject Visibility: A well-exposed image ensures that your subject is visible and properly illuminated. It allows viewers to appreciate the details and textures, enhancing the overall impact of the photograph.
  • Creative Control: Understanding exposure gives photographers creative control over the final outcome of their images. By deliberately adjusting exposure settings, you can manipulate the mood, highlight certain elements, or create specific effects.
  • Balancing Light: Exposure helps balance the dynamic range of a scene, which refers to the difference between the brightest and darkest areas. Proper exposure ensures that details are retained in both the highlights and shadows, preventing areas from being completely overexposed or underexposed.

Is Exposure the Same as Aperture?

No, exposure is not the same as aperture. Aperture is one of the three components that contribute to exposure, along with shutter speed and ISO. Aperture refers to the size of the opening in the lens that allows light to enter the camera. It controls the depth of field (the range of sharpness) in an image and affects the amount of light reaching the sensor.

Exposure, on the other hand, refers to the overall amount of light that reaches the camera sensor, taking into account all three elements: aperture, shutter speed, and ISO. While aperture plays a significant role in exposure, it is just one part of the equation. The combination of aperture, shutter speed, and ISO collectively determines the exposure value and affects the final outcome of the photograph.



If you want your photos to be properly exposed, you should also pay attention to the ISO value. You can brighten your images with an increase. However, as the ISO value increases, the image will become noisier. Image quality will deteriorate.

In some cases, there is no other option. An image with some noise is preferable to no image at all. In image processing, you can also reduce noise after the fact. As always, simply take the camera and experiment. That way, you’ll learn when to raise the ISO and when it’s not necessary.

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By Furoore team member Michael
Furoore Team is here to assist you in capturing the most significant moments in your life. To create exciting photographs, discover photography guides, find unique photo ideas, and limitless image inspiration.


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