Auto ISO and How It Works

Auto ISO is a feature that has saved the butts of many photographers since its inception, and also makes life easier when the camera does the work itself. Here's how to get it set up and dialed in, and learn what exactly the setting does.

Steve Perry loves his Nikon cameras, so in this video he is talking specifics with his favorite brand, but if you shoot with Canon or another manufacturer's camera, it's easy enough to follow along too. Auto ISO will be featured on most newer DSLR and mirrorless cameras these days, and the way it's set up and how it functions is similar across the board.

Perry does offer a little cheat sheet of his preferred maximum ISOs for a variety of different Nikon cameras, however. If you shoot something else, you may already know the limit that you are comfortable with or you may want to do a simple test to find out where the image starts to deteriorate beyond your satisfaction. On my Canon 7D Mark II I have the limit set at ISO 1,600, however I've heard other people capping this camera at ISO 800.

Do you use Auto ISO or do you prefer to control your camera manually? Share your thoughts in the comments.

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Dusty Wooddell's picture

I never use auto ISO for portraits or studio photography, but for events, I love it.

In controlled environments I cannot imagine why you'd need it. Shooting macro is another genre which auto-ISO can wreak havoc with important details.

Lee Stirling's picture

Steve Perry is a nature/wildlife shooter, so Auto ISO would be a very important setting for his work. He should know how high he's comfortable shooting with whatever camera body he's using and with whatever lens he's got attached. I think his videos on Nikon products are really helpful, useful, and easy to follow.

What on Earth has that got to do with my comment about not using auto ISO in a controlled environment? If you are in a studio where you can control the lighting you should absolutely not be using auto-ISO you should be shooting at the lowest ISO and adjusting your lighting.

Xander Cesari's picture

My camera is generally either set to base ISO for tripod work (landscapes) or auto ISO, usually in conjunction with aperture priority mode. It does exactly what I would do if I was manually controlling everything just way faster. Increase shutter speed at the base ISO until I hit around 1/30th of a second (slowest I can consistently hand hold without bracing up) then increase ISO until my noise limit. I couldn't really find a good reason to spin all those dials myself when the camera will do exactly the same thing instantly.

Rod Kestel's picture

While I'm more than happy (mostly) to shoot non-flash in Aperture mode, I never use Auto ISO.
Am I too hard-line? For unpredictable lighting at events, maybe I should soften that approach. I have to constantly watch shutter speed and even then blown too many photos where I didn't notice.

Mmm, maybe it's that my 7D Mk1 doesn't allow me to limit the auto. Maybe the software update will fix that...

Craig D's picture

Don’t use it if you’re doing landscape photography or portrait shooting, but it’s excellent if you’re out on the street shooting different subjects on the fly. I usually shoot in manual with auto-iso. Saves you time.

Used Auto-ISO for the first time at a baseball tournament..... Not bad. I'll probably use it again, especially for sports where the lighting is either slightly changing or dramatically changing because I need to keep my settings at a certain point in order to keep the action "frozen". Definitely beats going back and forth and constantly changing shutter speeds and apertures..... Also, frees my mind from constantly having to think about it!

Rob Mitchell's picture

I've tried it so many times but can't get on with the fact that it tried to boost stuff when I don't want it.
I can imagine there are probably situations it can be helpful, The only time I've been happy with it was at an event, other times I have plenty of time to juggle settings myself.


I love it for general shooting.

Why the HECK, does it work in MANUAL mode.
Has the meaning of the word: manual, been redefined?
Manual should mean manual, no IFS no BUTS, just everything in manual. NO AUTO ISO.
Where is the logic?
When I put a camera in manual, I expect to have FULL control of settings, every thing is as I want. MANUAL = MANUAL, not MANUAL = SEMI AUTOMATIC. Is that too much to expect?
I know a lot of photographers love it, but it should be a (switchable) FEATURE not a MISTAKE.
When I first came across it on a D700, I thought what a good feature, until I did a shoot with studio flash.
I could not figure out what the HECK was going on, lots of research later, I re-booked the shoot, as all exposures were being modified by auto ISO, in manual, really.
I too now shoot on D850, still has same error, but I know of the fault, so must correct for it.
When is a manual camera not a manual camera? When it is a Nikon!
Why bother with manual setting, if it can get screwed up. In my eyes it certainly is NOT a TRUE manual setting.
Give a name: Manual Auto ISO, haha. That looks really logical…
Then SELL it as a feature.
Do other manufacturers 'offer' this ridiculous/fantastical feature?

Auto ISO makes a lot of sense to me, as an option in Manual mode.

The traditional PASM structure is normally quite inflexible. Aperture priority mode lets you change the aperture, while the camera automates shutter speed and ISO. Shutter priority mode lets you change the shutter speed, while the camera automates aperture and ISO. Manual mode (without Auto ISO) lets you / forces you to control all three exposure parameters.

But what if you want to control two parameters and let the camera automate the third?

That's where Auto ISO in Manual mode is helpful. It lets you control two parameters (aperture and shutter speed), while the camera automates the third parameter (ISO).

Having the option of Auto ISO in Manual mode gives photographers more ways of using their camera, and more choice in how much control they want to have vs how much control they want to delegate to the camera. And that's good.

PS: kudos to Fuji for ditching the PASM structure and letting photographers control however many exposure parameters they want, and set whichever ones to Auto that they want to delegate to the camera.

Your first line say's it all, an option...
If a camera is set to Manual, then it should mean Manual.
If any maker wants to 'add' auto ISO, then is should be an OPTION, a 'NEW' feature, something for the maker to Shout about, a wonderful 'NEW' feature,not one that defies logic of settings, i.e. MANUAL.
This was not a feature of any camera I owned in the previous 30+ years EVER had. They all started of manual, then progressed to semi automation then full automation.
Yes I know now, that it is easy to turn off, but WHY should you have to remember that manual MIGHT mean manual. We might as well start saying black = white, if you do not remember the trick of saying it does not, if you selected an 'auto' switch earlier on. Defies LOGIC, bizarre.
Yes I love the feature, just in in its current implementation. Bad programming, Nikon.

Wonder Woman's picture

hah, manual mode auto ISO is one of the best features of a Nikon camera.

manual mode auto...
Not logical mr spock.

Wonder Woman's picture

Yes, I'm sure in the history of all manual things ever made, none of them have ever had any 'auto' functionality happening at the same time. When I ride my manual transmission motorcycle, I smash a rock against a piece of flint to ignite the gas in the engine.

You know you can turn it off by pressing one button and turning one dial?

I love having auto ISO in manual, it's incredibly useful and flexible. But turning it off just means holding the ISO button and turning the front dial. Very easy.

Yep, great feature, poorly designed implementation

Robert Teague's picture

I use a fixed ISO when shooting landscapes on my Z7, but for travel I use Auto. I'm still trying to determine what my max ISO should be on the Z7. My previous camera, D800, I kept it around 1600.

Love auto ISO but stopped using it a long time.
Most of my shoots are in controlled environment and with Speedlite on manual mode it can be a problem with changing distance (messed up a couple of wedding photos).
I shoot full manual and don't think am going to change any time soon.

I really like using Auto ISO so much so that I even reprogrammed the Movie-record button on my Nikon D750 to control ISO. I quick push of the button and flick of the front command dial turns Auto on and off. Works similar to the native ISO button on the D850. I've set the maximum to 8000 on my D750. If I go higher than I make the conscious decision to push it higher. I like how the Auto minimum shutter speed changes based on the focal length of my lens too.

Comes in handy for street but cityscapes and such manually setting the ISO is best I feel.

EL PIC's picture

On film cameras ... you can push process Film Speed but not varry it on different frames for a single roll.
One of the beautiful things about Digital is you do not have this limitation.
To each his own ... but Auto ISO is a 21st Century Innovation.
Quite helpful when I was shooting in very dark Antelope Canon ..