Photography Advice

The Must-Try ISO Tolerance Test: Max Out Your Mirrorless

Rethinking Photography in the Mirrorless Digital Age - Exposure - Part 3

What the Heck?

Admit it, you have never heard of ISO Tolerance or an ISO Tolerance Test, and you are irritated that I came up with a new photography term for you to learn.

You will thank me later for this and the straightforward workflow I will share in part four.

I joked in part two of this series that photographers already shooting digitally in the early 2000s likely suffer from digital noise PTSD. In those early days of digital photography, raising your ISO as little as two stops would often cause unbearable noise. In addition, the noise in the early digital cameras was not like the noise we experience from our modern mirrorless cameras; it was MUCH worse!

On top of that, somewhere between 2005 and 2015, probably as a reaction to that horrible noise, most photographers developed the mentality that any noise in a photo was terrible, regardless of the ISO.

This reaction led to “pixel peeping” and setting unrealistic expectations of what was acceptable and what wasn’t. I don’t know about you, but I like a little “texture” in my images. Not quite as much as the grain from the film days, but just a hint of texture. I feel it helps with the mood of the photo.

📸 Did you know?
The human eye, glorious as it is, can’t actually resolve individual pixels at typical viewing distances. So, unless you’re planning to inspect your print with a magnifying glass, pixel peeping is likely to be a futile exercise in frustration.

What Is an ISO Tolerance Test?

An ISO tolerance test will tell you the highest ISO you are comfortable shooting at on any camera. 

You should do this test on every different camera model (no need to do it on two cameras of the same model) that you own, and you should do it every time you purchase a new camera model.

The Set up

The test is simple to do. Place your camera on a tripod. A table or chair will do just fine if you don’t own a tripod.

Your camera needs to be set on Manual Exposure, and you begin with your ISO set to the base ISO.

If you don’t know your camera’s base ISO, check your manual or ask Google: “What is the base ISO of (enter camera brand and model number)?” Most cameras sold today have a base ISO of 100 or 200.

Step 1

Use your camera’s light meter to determine the correct exposure (Shutter Speed and Aperture) at the base ISO. Shoot 1 frame. (This is one of the rare times I will tell you to rely on your cameras light meter.)

Step 2

Raise the ISO by one stop, adjust your shutter speed or aperture so that your light meter lines up again as a proper exposure, and then shoot another frame. No need to do third or half stops for this test.

If you are new to photography or have yet to learn what the ISO numbers represent (The correct answer is not sensitivity!), one stop is double the number. So, if your base ISO is 100, your second photo will be made at ISO 200. If your base is 200, your second photo will be at ISO 400.

Step 3

To continue the test, you will double the ISO number (Increase by one stop) and adjust your shutter speed or aperture to ensure your meter shows a proper exposure. Then, shoot another frame.

Repeat this for every ISO.

If you start at 100 ISO, you will make test images at 100, 200, 400, 800, 1600, 3200, 6400, 12,800, etc.

If you started at 200 ISO, you would make test images at 200, 400, 800, 1600, 3200, 6400, 12,800, 25,600, and so on.

** There is NO need to do 1/2 or 1/3 stop ISO settings. They will have very little impact on the test results. (1/3 stop ISOs ex: 100 125 160 200 . . . etc.)

Continue this process up to the maximum ISO that your camera allows.

Note:  I encourage you to do the test indoors, as getting a correct exposure at your maximum ISO will be easier.

Step 4

Download the images (1 frame at each full-stop ISO from the base ISO to the camera’s maximum ISO) to your computer and open them in whatever software you use for culling. I use Adobe Bridge, and most of you will be using Lightroom; it could be Luminar NEO. Use the software that you routinely use to develop your photos.

Step 5

Starting with the image shot at your base ISO, view each image at 100% on your screen (the same screen you typically use to process your photos). Do not enlarge the image greater than 100%, and do not lean in real close or use the magnifier loupe in your software.

View each image in the order you shot them until you reach the image where the amount of noise is objectionable or “beyond your tolerance.”

Once you find that image, the ISO of the previous image is your ISO Tolerance. 


Your ISO tolerance is the highest ISO you are comfortable shooting with on any given camera without using noise reduction software or AI noise tools.


This number is an essential reference as we work on simplifying your approach to exposure in Part Four of this series. I have no doubt that with the advancements in noise reduction software and AI tools, it will not be more than 5 years before we won’t need this reference, but for now – while the noise reduction tools are indeed excellent – they are far from perfect so this step remains essential.

Video Example of the ISO Tolerance Test

The video below shows the actual ISO Tolerance Test for my Sony A7IV camera bodies.

You can see that I photographed my mannequin, Lola (If you purchase a mannequin, you must name them. It’s a thing! The Internet said so.) next to a window.

Having a mannequin or even a person to do the test is not necessary; you can photograph whatever type of setting is most like your typical type of photography. 

Including dark shadow areas (the black material I placed behind the mannequin) and bright white areas (the diffused window) in the scene you photograph is a good idea to see how the noise will react as you raise the ISO.

I included the 2X magnifier in the video clip to make it easier for you to see the noise as it appears. Remember, when you review your images. – you should only review them at 100% – No “pixel peeping!”

The Results:

For me, 6400 ISO is totally within my tolerance. Depending on the use of the photo, I may apply a slight amount of noise reduction, but nothing aggressive, and definitely no need for AI noise reduction at that ISO.

I have no problem working at 12,800 with the knowledge that I will definitely apply noise reduction in post-production. With the current software in 2024, I would use AI Denoise in Adobe Camera RAW at about 45% with this ISO.

Considering the last two statements, I have set the MAX ISO Limit in my Sony A7IV to ISO 8000.

Anything shot up to 8000 that is correctly exposed will need minimal if any, noise reduction for my needs.

By setting the MAX ISO Limit, if I am ever faced with a need to go above that, my camera will notify me, and I will make the decision on a case-by-case basis.

Maximum ISO Is What Makes This Test So Valuable

Every mirrorless camera sold today and many DSLRs will allow you to set a Maximum ISO for the AUTO ISO feature in your camera.

Refer to your camera manual to find this setting in your menu. Use your ISO Tolerance results – the highest ISO you are comfortable with – to set the maximum ISO.

Remember, this only impacts AUTO ISO. Your camera can still work up to its maximum advertised ISO, but you will have to make a conscious decision whenever you want to exceed your ISO tolerance. 

This will help ensure that you never inadvertently wind up shooting images at an ISO that will deliver results you will not be happy with. 

The Final Frame

This simple and instrumental test will take 30 minutes from start to finish, depending on your experience level. You only need to do it one time per camera model.

It will take the guesswork and assumptions out of knowing how high you are comfortable setting your ISO without having to rely on software to improve your image.

I realize that some reading this may still struggle to understand the value of the information I provided. PLEASE read on to the following article – Part four of this series. I will share a quote that will forever change how you approach setting your exposure.

If you still need to read Part 1 and Part II, I would encourage you to check them out.

I hope you found this information useful. Now go pick up that camera and shoot something! Because – “Your BEST shot is your NEXT shot!” — Joe Edelman

Have more questions about becoming a successful photographer? Would you like to continue the conversation? Join my TOGKnowledge Photographic Community, where you will find photographers from over 30 countries passionate about learning and sharing their photography as they develop their craft.


The Exposure Series

Part I: What the Exposure Triangle and Brooklyn Bridge Have in Common 

Part II: Demystifying Digital Camera Sensors: The Journey of Light to Pixel

Part III: The Must-Try ISO Tolerance Test: Max Out Your Mirrorless

Part IV: Use Purpose and Feeling for Correct Exposure In Every Frame


Joe Edelman

Joe Edelman is an award winning Photographer, Photo Educator and the host of The The LAST FRAME LIVE, which is viewed by photographers in over 100 countries.  Follow this link to learn more about Joe or view his portfolio.
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