How to Take Advantage of Auto ISO

You can trust your camera to do the right thing.

Mark Ali


A mode dial on top of a camera.
Image by the author (© Mark Ali)

We all know about the “exposure triangle”, right? It’s one of the first things you read about when you learn the basics of photography. Shutter speed, aperture, and ISO make up the triangle, and their settings determine your exposure.

I may write an article about that someday. (There are a lot of articles out there about that topic. But I like to put my spin on things.)

Anyway, most of us are comfortable with using “Aperture Priority” mode and “Shutter Priority” mode on our camera. Some manufacturers use different names for these modes, but the function is the same. You set one value (aperture or shutter speed) and the camera adjusts the other value (shutter speed or aperture, respectively) to give you a proper exposure, based on the camera’s metering.

But there’s a common camera feature that many folks forget about, and that’s Auto ISO.

Most of us set an ISO value manually — typically the lowest value appropriate for the situation — and we leave it there. And that’s fine. But if we’re ok with the camera setting shutter speed or aperture automatically, why not ISO?

Manual Mode with Auto ISO

One of my favorite ways to shoot is to set my camera to Manual mode, with Auto ISO enabled. In this configuration, I have complete control over the “creative” exposure settings (the shutter speed and the aperture) and I let the camera decide the ISO. Most cameras make good decisions about this and try to keep the ISO as low as possible.

If you’re new to Auto ISO, you might be thinking: “I don’t want the camera to make my ISO skyrocket! It’ll just make noisy images!

You’re correct to be concerned.

Though you’re also a little too excitable — you really need to relax.

And you can relax because the Auto ISO feature on most cameras these days allows you to set a maximum ISO, thereby restricting the camera to ISO values that are at or below that value. I set mine to the highest ISO that I think my camera can handle without unacceptable noise — usually either 800 or 1600. If you look at the image below, you can see what these settings…



Mark Ali

I’m a writer, a photographer, a music lover, and a professional ice sculptor. I’m kidding about that last thing. (View my portfolio at: