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Photographers seem to be obsessed with ISO invariance, you’ll hear almost every digital photographer discuss this, but the question is: what is ISO invariance?

If you want to understand what ISO invariance signifies, then you are in the right place. The core meaning of ISO invariance can be long and specialized, but in this article, I’ll explain everything with ISO invariance examples in an easy-to-digest way.

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Many misconceptions exist regarding how our camera sensors work with ISO settings. This article will explain what ISO invariance is, whether an ISO-less sensor is superior, an ISO invariant camera list, and more. Let`s begin directly!

Note: All through the article, you’ll see the phrases ISO invariance and ISO-less, but they both mean the same thing.

What is ISO Invariance?

Short answer: A camera sensor that is invariant to ISO will generate the same results in relation to image quality if you underexpose your photograph and subsequently raise theexposure in post-production as if you had correctly exposed it (in camera) originally.

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Still wrapping your head around it? Don`t worry, I`ll explain everything in more detail with plenty of examples without ISO settings to help you understand this concept fully. But before continuing, to comprehend this article fully, you need to understand how ISO functions in digital photography by reading our dedicated article on the topic.

Before proceeding further, let’s clarify one widespread misunderstanding regarding ISO:

    • Analog ISO and digital ISO operate differently. In analog photography, ISO is the sensitivity of the film used at a given moment. This definition has spread to digital photography; however, ISO in the digital world is not the sensitivity of the camera’s sensor to light, it’s an artificial signal magnification that brightens the image .

Why is ISO invariance important?

There are some light situations where ISO invariance is very important.

Imagine you are snapping the Milky Way in a place with outside lights. On the off chance that you expose your photograph accurately, the lights will most likely be clipped overexposing regions in the last photograph. To amend this, you need to underexpose the picture by lowering the ISO in your ISO-invariant camera.

When you return home and edit your image, you just need to raise the shadows to achieve the proper exposure in your image. This simple action will preserve the information and detail in the lights, while having the identical digital noise that you’d have by shooting at a higher ISO.

Another good example is Northern Lights photography, where you shoot in a dim environment where there are very strong luminances (the Aurora Borealis) that can be overexposed in your images.

a person on a cell phone taking a picture of a sunset

Essentially, ISO invariance becomes important when there is a high dynamic range, which is a scene with very bright highlights and very dark shadows. In these types of scenarios, it’s more important to preserve detail in the highlights by underexposing and then pushing up the shadows in post-production.

If you have an ISO-less sensor, raising the exposure in post-processing will reveal the same amount of noise as exposing correctly in-camera using a higher ISO. This will have the added benefit that you’ll preserve detail in the highlights, which will allow more flexibility to edit instead of having overexposed highlights.

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Note: when researching ISO invariance, you may come across discussions involving “light particle” noise and “electronics” noise. Light particle noise is produced by photons (light particles) in the scene and exists regardless of the camera. Electronics noise arises in camera components during image capture. An ISO invariant camera exhibits negligible electronics noise values. .

Camera Models with ISO Invariance

Locating an ISO invariance camera listing is not an easy task. Manufacturers fail to provide ISO invariance as a specification for their cameras, thus if you want to know if your camera is ISO invariant, you must conduct some tests.

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However, we’ve tested different cameras and researched other models, presenting here a complete list of cameras with full ISO invariance:

This is likewise an accessible ISO invariant camera register, there exists numerous additional models, some of which are getting published now or have not yet been evaluated. If you`ve examined a model that is not on the list, please inform us!

Some camera models are only ISO invariant within certain ISO ranges. To compare ISO values between different camera models, you can use the Image Comparison Tool on DPReview. To find more detailed charts you can check the Photon to Photos PDR Shadow chart.

Also, don’t overlook our article about the prime cameras for photographing the Milky Way galaxy if you are searching for an excellent camera for low-light photography.

Is your camera ISO Invariant?

Testing if your camera is ISO invariant is a fairly simple task. You’ll only need three tools: your camera, a tripod, and an editing software like Lightroom.

Test if your camera is ISO invariant with these basic steps:

    1. Capture a foundational image: secure your camera on a tripod. Configure your camera to manual mode (M). Photograph a subject at ISO 6400, and expose it adequately. This will serve as your baseline photo.

Tip: photograph a simple and stationary subject. If you possess a gray card or a color chart, you can utilize that, otherwise, you can employ any surface with multiple details, in my situation I employed the magnets on my fridge.

a collage of photos and stickers on a refrigerator

    1. Photograph test exposures: now, lower the ISO to your camera’s base light sensitivity setting, generally ISO 100, and photograph the same subject. The shot will be underexposed, as intended. Take additional test shots, in 1/3 stop increments until reaching ISO 5000.

Note: Most contemporary mirrorless cameras employ a dual-level ISO structure. For the aims of this article, this implies they are ISO changeless in two diverse ranges. See Photon to Photos site to look at the dissimilar ISO intervals in your precise design.

    1. Harmonize the exposures in Lightroom: on this final action, import all the pictures you took into the digital media editing tool of your choice. By manipulating the exposure slider, adjust the exposures on all the test shots to match the control image. In Lightroom, you can easily synchronize all the exposures by choosing all the media files in the Develop module and going to Settings –> Synchronize Total Exposures.
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    1. Compare the noise you see in all the shots: If you see little or no difference between the test photos and the control photo, it means your camera is ISO invariant .

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Best ISO Invariance Tips

To make the fullest use of your ISO invariant camera, there are a few elements to keep in mind.

The concept of ISO invariance is something every photographer, either professional or beginner should be aware of. If you are reading about ISO invariance in this article, then you’ll most likely value a few recommendations.

    • Photograph in RAW: none of the material in this article applies to JPEG images. This is likely the top photography suggestion for novices; If you are serious about photography and want to maximize the capabilities of your camera, you should be capturing in RAW.
    • Deactivate in-device sound reduction attributes: most cameras have a extended presentation commotion decrease and a high ISO noise decrease include, with just the earliest influencing the RAW documents. In any case, it’s a decent practice to inactivate these regardless of whether your camera is not ISO-less. This is one of the principal things I change when I to begin with set up my cameras.
    • Employ inherent ISO values: for the best picture quality and ISO invariance outcomes, don’t utilize any of the expanded ISO values in your camera. These are simulated ISO values and don’t offer any real benefit when using them. These expanded values generally contain any ISO value under 100 and over 51200 in most cameras. You can check the exact values on your camera’s spec sheet.

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    • Do not fear underexposing: most contemporary cameras have an outstanding shadow restoration, but not such good highlight restoration. When given the choice, it’s always preferable to underexpose about 1 to 2 stops to maintain detail in the highlights and then brighten the shadows in post.
    • Don’t excessively increase the exposure slider: even if your camera is ISO invariant, your RAW photo editor won’t do a great job when you excessively increase the exposure slider too far, and you might start seeing strange color artifacts. I generally don’t like to brighten my photos more than 4-5 exposure increments in post-processing.
    • Employ some noise reduction software: Using ISO invariance techniques, you’ll protect the highlights, but you won’t eliminate the digital noise. To remove the noise and enhance your images, I suggest utilizing some of the top noise reduction software available.
    • Know your camera: run tests, review ISO charts, and practice. To obtain the best image quality from your camera, it’s important to master all the basics of photography and be familiar with your sensor .

ISO Invariance Examples

ISO invariance is best understood with some visual examples. I’ve taken a few shots in different scenarios to demonstrate how a camera without ISO settings should behave.

ISO Invariance in Astrophotography

Astrophotography benefits greatly from ISO invariance, being able to reduce the ISO to protect the highlights and then bring up the shadows in post-processing without compromising quality.

an aerial view of a mountain with a sky background

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ISO invariance in Northern Lights Photography 

Capturing the Northern lights is another typical challenging lighting scenario where you can encounter darkness accompanied by very luminous lights. To successfully recover the highlights in all those instances when the aurora strongly radiates in the sky, you can decrease your ISO if your camera has invariant ISO properties and secure spectacular Northern Lights photographs!

a sunset view of a large body of water

Decrease your ISO when photographing Northern lights to protect the highlights.

ISO invariance in Star Trails photography

By capturing images at a lower ISO value, you can maintain the natural color within the stars when you [photograph star-trails] while achieving the same level of digital noise within your image. This is the only approach to capture a star-trail photo with the genuine color of the stars.

an aerial view of a tree filled with colorful flowers

ISO Invariance in Landscape Photography

When photographing scenes with a wide range of brightness levels in landscape photography, it is beneficial if your camera does not have fixed ISO settings. Being able to deliberately underexpose slightly to protect the highlights will be advantageous when editing your image using Lightroom or another editing application.

a forest filled with lots of trees and shrubs

ISO Invariance FAQ

This topic raises numerous inquiries and finding a clear concept of ISO invariance is not constantly effortless. In this section, I’ve gathered the most frequent questions asked concerning ISO invariance:

A camera that does not change based on the ISO used (ISO-invariant) will reveal an equivalent amount of noise if you decrease the exposure of a photograph and brighten it later in post-production as if you exposed it accurately in the camera.

Some scenarios could necessitate intentionally underexposing a photograph to retain detail in the highlights. With a camera that maintains image quality regardless of exposure settings, one can then lighten the shadows in that image and acquire identical image quality and noise levels as if correctly exposed in-camera, with the added benefit that highlights won’t be truncated.

This passage summarizes some devices that capture images with little to no distortion:

Sony:

Canon:

Nikon:

Fujifilm:

To examine if your camera produces consistent images regardless of ISO settings, follow these simple steps:

    1. Capture a photo of a stationary subject at an ISO of 6400 in RAW format.
    2. Take test shots of the identical subject at an ISO of 100 and further photos at increments of 1/3 ISO until 5000.
    3. Import all the photos into Lightroom or any other photo editing software.
    4. Adjust all the test images to match the exposure of the ISO 6400 image.
    5. Contrast the test photos with the one taken at ISO 6400. If the noise visible is pretty much consistent, then your camera is ISO invariant.

If a camera detector lacks a predefined ISO it doesn’t indicate it has improved image quality, it simply implies more versatility will exist when editing RAW files in a photo editor in those high dynamic-range situations.

Conclusion

To summarize briefly, this is the key meaning of ISO invariance: an ISO invariant (ISO-less) camera will produce the identical outcomes if you sub expose a scene and then brighten it up in a photo editor as if you exposed it correctly in camera. The main benefit is that you’ll protect the highlights from clipping and you’ll have more detail and data in the highlights of your image.

ISO invariance definitions can become extremely technical since it’s a complex topic. In this ISO invariance article, I’ve tried to break down the explanation into easy-to-grasp sections with simple language to facilitate comprehension. I hope after reading this article you can understand the difference between a standard and an ISO invariant sensor.

If you want to gain more knowledge about this topic, I highly recommend verifying our dedicated guide to ISO in digital photography.

Please, feel free to post a comment below with any question you might have related to ISO invariance and I’ll be more than happy to help!

Happy captures!