ISO settings represent a core photographic concept together with aperture and shutter speed. It occupies a vital role within the exposure triangle and impacts what camera configurations will produce the desired exposure
In the field of photography, ISO serves as a basic tool to heighten the brightness of imagery under low light conditions or when faster shutter velocities are necessitated, but care must be exercised since employing heightened ISO sensitivity values can undermine the ultimate quality of photographic results.
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- Definition of ISO in Photography
- How image sensitivity is quantified in digital cameras?
- How camera ISO can be used to correct exposure
- How to choose the suitable ISO setting
- How ISO and digital noise are related
- Examples of ISO photography
Table of Contents
What is ISO? ISO in photography definition
ISO in photography can be described as a way to increase the light data captured by the camera sensor.
Too specialized? No worries – continue reading and I guarantee by the end of this article, you’ll grasp what ISO signifies in photography.
The important aspect before delving deeper is to eliminate two misapprehensions:
- Historically, ISO in photography origins from the abbreviation “International Organization of Standardization” and a time when camera manufacturers needed to make the sensitivity ratios in film cameras consistent. Today, ISO in digital cameras doesn’t follow the standards of the ISO organization.
- Despite what many people still think, ISO in digital photography has nothing to do with increasing the light sensitivity in the camera sensor. However, there are still photographers who wrongly refer to this term as ISO Sensitivity in digital photography.
One of the optimal photography recommendations for novicesis to recognize what ISO refers to through practical exercises in which you vary this setting manually.
How ISO in photography works
The primary impact of ISO on image capturing is that it digitally augments the light caught by the camera`s optical sensor, ultimately yielding a lighter final photograph.
In straightforward terms, ISO in photography acts in the following way:
- The camera sensor collects a quantity of light that depends on the aperture of the lens and the duration that the sensor is exposed ( shutter speed). This light facts is also referred to as “Signal” in photography.
- When this lightwave is perceived, ISO plays a role in interpreting it. This interpretation relates to the amplification of the lightwave.
- When ISO boosts this signal/light, the final picture will be brighter, but it will progressively start generating more digital noise as you raise the ISO, compromising the ultimate quality of the image .
ISO levels in photography: How ISO is measured in digital cameras?
ISO levels in photography follow standard scales in most digital cameras, and the most common ISO progressions today follow this pattern:
As shown, each ISO step in photography is double the previous number, which corresponds to doubling the light in your photograph as you raise an ISO step.
This ISO level range is commonly referred to as “Native” ISO in photography, but, today, some digital cameras allow higher ISO values to be set, such as, for example, ISO 25600 or even ISO 51200. They are also constructed to set lower ISOs below 100, such as ISO 50 or ISO 25. These ISO numbers outside the standard or “Native” ISO are called “Extended” ISO .
How to use camera ISO in photography
Considering the preceding explanation of how ISO affects photography, you’ll utilize the ISO to decide the final settings in your image.
The ISO should consistently be utilized in photography in relation to the aperture and shutter speed. All three comprise the exposure triangle and you must aim to strike a balance among the three while considering the light of the scene and your photographic aims.
For instance, with a fixed aperture, doubling the shutter speed from 1/2000th to 1/4000th of a second requires increasing the ISO one stop to maintain consistent exposure.
Below you’ll see which instances to use a determined ISO in photography.
When to use a low ISO in photography?
To capture quality photographs, the main goal is to set a Native ISO as low as possible.
As mentioned previously, increasing the ISO progressively utilizes your camera sensor`s capacity to “generate” a brighter image, translating to digital noise.
Base ISO is the minimum Native ISO level, and it’s the ISO that you should aim to employ when conditions allow. In most cameras, Base ISO is ISO 100.
ISO values like ISO 200 and ISO 400 are also considered low ISO values in photography.
Examples wherever you ought to establish a low ISO in photography are all scenes with ample light and where you don’t necessitate a speedy shutter speed.
When to use a high ISO in photography?
However, it’s not all rainbows and sunshine, and you’ll often encounter challenging light situations where you’ll be compelled to utilize a high ISO in photography.
High ISO values in photography are mostly used in low light situations or scenarios where you need a fast shutter speed.
Using a high ISO in night photography is one of the most frequent scenarios for using high ISO values, since some scenes such as capturing photos of the Milky Way will necessitate pushing the restrictions of your camera to record a dark landscape within a comparatively brief exposure period.
How to set the ISO on your camera
As mentioned in our guide about camera settings,each model of camera has its own configuration for ISO, so you must check how to alter the ISO on your particular camera according to its brand.
All cameras offer a fast button to vary it, since ISO is one of the most crucial photography fundamentals and a setting that demands constant modification.
In fact, most camera modes, even semi-auto modes, don’t set the ISO for you. However, you can configure the Auto ISO so that the camera itself chooses the optimal ISO.
If selecting this option is chosen, the advice given is to establish a maximum ISO to avoid digital noise issues and in case the subject moves rapidly, set a minimum shutter speed to ensure sharp photos are captured.
What’s the best ISO? How to choose the right ISO settings
As with the aperture and shutter speed, there is no most suitable ISO to fix on your camera, since it’ll totally depend on the light circumstance and the motion that you want to capture.
The only situation in which what is the optimal ISO is clear is when there’s ample light at a stationary scene (with no objects that move rapidly). In these cases, you’ll use the Base ISO (100 or 200 depending on your camera) to achieve the best quality results.
To give you a rough idea, below you’ll find the ideal ISO settings in various photography genres:
ISO and digital noise are completely related, and this is the most significant thing to consider when you need to raise this setting.
As noted in the section on the operation of ISO in photography, increasing the ISO artificially heightens the light levels captured in images, and this light amplification concurrently increases the quantity of grain and visual disturbances within photographs.
It is essential to have an understanding not simply of what ISO is regarding photography, but also how ISO impacts your images as per your camera model, since the sensor size and brand will likewise play a key role in establishing the ultimate quality and sharpness of the image.
To further explore, I also suggest examining our articles on how to lessen digital noiseby using the suitable settings and which is the top noise reduction software.
ISO photography examples
To finish this ISO photography guide and help you comprehend what ISO is in photography, below you’ll find some ISO photography examples where you’ll see ISO settings used in different light situations and the reasons for setting that particular ISO.
- Capturing the movement when taking photographs of the Northern Lights,requires utilizing a higher ISO. The side effect is having more digital noise. The goal is to strike a balance between detail in the Aurora and an acceptable amount of noise:
ISO examples shooting Northern Lights.
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ISO 2500 f/2.8, 4 sec. (Left) ISO 5000, f/2.8, 1.3 sec (Right)
- To photograph sharp stars in a dark landscape, you’ll have to heighten the ISO to prevent a long shutter speed and star trails. Again, digital noise will be a byproduct of raising the ISO in this type of scenario:
ISO examples for starry landscape photography
ISO 3200, f/2.8, 30 sec. (Left) ISO 6400, f/2.8, 25 sec. (Right)
- To photograph wildlife in low-light conditions, you’ll need to raise your ISO to compensate for the lack of light and the usage of a telephoto lens.
ISO examples of wildlife photography
ISO 4000, f/5.6, 1/40 sec. (Left) ISO 6400, f/5.6, 1/30 sec. (Right)
ISO F.A.Q.
Beneath you’ll discover reactions to a portion of the most regular inquiries about understanding ISO in photography:
What is ISO in photography?
ISO refers to the camera sensor`s sensitivity to light. It`s part of the exposure triangle, along with aperture and shutter speed, which determines how much light enters the camera.
How does the ISO Setting Impact a Photo?
As you gradually increase the ISO, your image will be brighter, but there will also be more digital noise.
Which ISO setting should I apply?
When lighting allows, use your camera`s lowest inherent ISO, also called Base ISO. In most cameras, Base ISO is ISO 100 or ISO 200.
What is Native ISO?
Built-in ISO is the optimized ISO level incorporated into your camera. Most cameras have a Built-in ISO range from ISO 100 to ISO 6400
What is Extended ISO?
Extended ISO refers to additional ISO values provided by some camera manufacturers that are outside the standard ISO range. Some devices can lower the ISO setting below ISO 100 or increase it above the highest standard setting, such as ISO 25 or ISO 25600 respectively. Utilizing these non-standard ISO values is generally not advisable as it requires an extreme adjustment of light sensitivity that can reduce the quality of captured images.
What is the optimal ISO for nighttime photography?
When photographing stars or the Milky Way, using a high ISO setting will obtain images with low light for a specified duration so stars are caught as sharp spots instead of trails. In most full-frame cameras, the ideal ISO range for night photography commonly falls between 3200 and 6400.
Conclusion
After all the theory and seeing some ISO photographic examples, the best way to really understand what is ISO in photography and how ISO works is to start practicing!
Photograph scenes with differing light and different ISO levels, and zoom in on the images later to see how the exposure and digital noise vary, the two primary impacts of ISO in photography.
To fully understand ISO and how it impacts exposure, I suggest examining our beginner’s photography guide (or downloading it as a PDF guide here) and the articles about the other two fundamentals in photography:
Gaining a fundamental understanding of the concepts below is recommended:
I hope this guide to ISO in photography helps expand your understanding about this important topic and helps you capture stunning imagery!
