Changing ISO on the Sony a7iii (Easy!)

Looking to fully master manual exposure?

Although not a “creative setting” like shutter speed or aperture, ISO plays a crucial role in the exposure triangle.

In this quick and concise guide, I’ll be going over how (and why!) to adjust the ISO on your Sony a7iii.

Let’s dive in!

photographer with camera in low light

The Basics

Definition of ISO

To start off: what even is ISO?

Back in the days of film cameras, ISO used to measure the, for lack of a better term, “brightness” of a piece of film.

In the modern day, however, it’s much simpler. ISO is pretty much just a number used to measure how sensitive your camera sensor is to incoming light.

To put it in really simple terms: lower ISO equals darker images while higher ISO equals brighter images. When you double your ISO value, you’re essentially doubling the brightness. As an example: 400 is twice as bright as 200.

What is digital noise?

Although the ability the push your camera to sense more light may sound like magic, there are downsides to pushing your ISO value up.

Shooting at high ISO can introduce a concept called “digital noise“. Noise is pretty much damaged pixels that don’t accurately represent their original colors or exposure.

Anytime you see colorful grain/specs in an image, that’s digital noise due to pushing ISO values too high.

Notice the grain (digital noise) in the shadows due to high ISO.

How high can you go?

So, now we know not to push our ISO too high, but how much is too much?

The a7iii is a low light beast, and I’ve found I can get excellent results up to around 6400 ISO. Pushing beyond that, 8000 ISO starts to introduce some noise, but it’s still an entirely reasonable level.

If you’re really desperate for more light, 12800 still looks pretty solid, and I wouldn’t ever hesitate to push my ISO up that high if it meant I’d be capturing a great shot.

ISO 32000 is still usable and would work in a pinch, but I’d only resort to that if you’re desperate. The camera can, if needed, push all the way to 51200 natively (and can be expanded to 204800 at a major loss in quality).

What is base/native ISO?

On the flipside, ISO values can only go so low.

While it varies from camera to camera, the Sony a7iii offers a native/base ISO of 100, although it can be “expanded” down to 50.

It’s always best to shoot in the native ISO range (in this case, the camera’s ISO range is 100-51200) as opposed to the “expanded” range (50-204800) in order to retain the best quality (due to sensor hardware limitations).

How to Change ISO on a Sony a7iii?

Now that we’ve talked all about ISO, how do you actually change the setting on your Sony a7iii?

It’s quite easy.

  1. Make sure the camera isn’t in automatic mode
  2. Push the right side of the rear wheel (it says ISO)
  3. Select your desired ISO setting
  4. Refer to the image if needed

Yep, it’s as simple as that.

By the way, if you’re looking to just play around with ISO but don’t want to worry about other settings, switching the camera to “P” mode will keep everything else automatic.

High ISO helps capture dark environments.

When should I increase my ISO?

So, in theory you should increase your ISO anytime you need to get more light into the camera sensor.

However, due to concerns about digital noise, it’s not always that simple.

Avoiding Digital Noise

As I stated before, pushing your ISO value up will introduce digital noise which will degrade the quality of your pictures.

Increase ISO Last

Instead of pushing your ISO up as soon as it gets dark, try to adjust your shutter speed or open up your aperture first.

When I’m out shooting in low light situations, I try to only push my ISO up as an absolute last resort.

As an example, if I’m shooting handheld in the dark and I’ve already opened up my aperture or lowered my shutter speed as much as possible. Only then will I bump up the ISO.

Use a Tripod

Adding onto my previous point: consider using a tripod if possible. If you need to let in more light, always consider putting your camera on a tripod (or other stable surface like a table) before resorting to higher ISO.

Having your camera on a stable surface allows you to lengthen your shutter speed, thus allowing more light into the sensor without negatively impacting the quality of your images.

By the way, if you’re looking for a great tripod, my personal recommendation is this mid-tier tripod (affiliate link) from K&F. You can buy something more expensive, but I’ve really been happy with this cheaper option.

Reasons to Increase ISO

Now, there’s many situations where you’ll end up having to increase your ISO anyways.

So when should you actually do it?

Handheld in Low Light

As I alluded to earlier, sometimes you’ll find yourself in situations where you’re shooting handheld and don’t have the ability to use a tripod.

Some examples include: events that are in poorly lit buildings, lightweight hiking/travel or any other situation where a tripod would be inconvenient, heavy, or not permitted.

If you’re in a low light environment without a tripod, it’s always worth increasing your ISO (and risking digital noise) so you can still get the shot.

Fast Action Photography

The next reason to increase your ISO would be if you’re trying to capture fast action such as sports or racing.

To give an example: you’re watching a race as the sun is setting. You’re rapidly losing more and more light but still need to keep a fast shutter speed to capture movement.

Putting your camera on a tripod and slowing down your shutter speed would cause motion blur, so as a last resort you’ll have to push your ISO up.

toyota truck driving through water
Using a slower shutter speed would introduce motion blur, thus high ISO is needed instead.


The final reason to bump up your ISO would be if you’re trying to capture the night sky.

Although slowing down your shutter speed is by far the most important part of astro, ISO also plays a critical role.

Anyone who has photographed the stars before knows that having too long of a shutter speed introduces a concept called “star trails”, where stars will be “stretched” due to the natural rotation of the earth.

As a result, to get sharp points of light, you need to strike a balance between long shutter speeds and high ISO.


So yeah, ISO may sound complicated in theory, but it’s quite simple to understand when you start to get the hang of it.

My biggest advice would be to just get out there and practice. Take a variety of photos at various ISO levels and zoom in. Look closely at the digital noise, and eventually you’ll start to intuitively understand what the best ISO is for any given shooting circumstances.

Once again, ISO is only one part of the exposure triangle. If you’re still yearning to master manual exposure in your a7iii, check out my guides on shutter speed and aperture.

Thanks for reading!