Sony a6400 High ISO Tests with Sample Images

I’ve lately been out shooting with the new Sony a6400 mirrorless camera, the latest in the smaller APS-C cropped mirrorless cameras in the Sony Alpha range (they also have full-frame cameras in the Alpha range, such as the a7r III).

It has a 24.2 MP APS-C Exmor CMOS sensor and Sony’s BIONZ X on-board image processor. It’s an incremental release that slots in easily within the existing range of a6000, a6300, and a6500 cameras. If you’ve used one of those cameras–or, indeed, any of the recent Alpha cameras–the a6400 is going to feel instantly familiar.

I’ll be posting separately a detailed hands-on review and a more expansive set of sample images I’ve shot with the a6400. I’ve also posted side-by-side images shot across the entire spectrum of the a6400’s available ISO range from 100 through 102400.

What I’m focusing on here is the high-ISO performance when shooting photos in low light. Because as much as I like a good travel tripod, most of the time I find myself shooting hand-held. Specifically, I’m looking at images shot within the ISO range from 6400 up to 102400. Because not all of the available ISOs within that range are of the same kind, I’ve divided it up below into two groups: native ISO and extended ISO.

Native ISO vs Extended ISO

For still photos, the Sony a6400 has an ISO range from 100 through 102400. But not all of that range is equally useful. That’s because there’s a difference between the sensor’s “true” ISO range–also known as native ISO range–that’s down to the responsiveness of the sensor itself. The native ISO range of the Sony a6400 is 100 through 32000.

To get the ISO sensitivity above that, you need to tap into the extended ISO range, where the where software takes over to boost the signal and cleans up the image. In practice, the image quality drops off markedly in the extended range, but if it means the difference between getting the shot and not getting the shot, that might be something you’re willing to live with. Or maybe you like that look or are converting it to monochrome, which is a common way to mask some of the image quality flaws.

If you are shooting in that extended range, I’ve found that the camera’s own processing of JPGs does as good a job or even better than is easily accomplished through post-processing the RAW files. I normally shoot RAW, but this is one time when it’s often worth switching to JPG (or, better yet, using the RAW+JPG setting).

Examples of High ISO Images Taken with the Sony a6400

So here are some shots I’ve taken with the a6400 using ISO 6400 up through ISO 102400. These were all taken with the Sony 18-135mm ƒ/3.5-5.6 E-Mount lens, which I’ve been testing out at the same time.

The camera has in-camera noise reduction processing when shooting JPG images. That processing is also applied to the JPG thumbnail previews that are saved within the RAW file, but it doesn’t affect the underlying RAW data. The higher the ISO, the more aggressive the in-camera noise reduction is by default. But for these examples, I’m bypassing that by regenerating the JPGs directly from the RAW image. And I’m applying very little in the way of noise reduction–in fact, for these, I haven’t added anything beyond Lightroom’s default, which is quite a light touch. That makes it easier to compare apples to apples for the purposes here, but it also leaves quite a lot of room for post-processing noise reduction if you’re so inclined.

Native ISO Range: 6400 to 32000

These photos were shot within the a6400 sensor’s native ISO range of 6400 through 32000. You can click on each image to open a full-size version for a closer look.

Extended ISO Range: 40000 to 102400

These photos were shot within the a6400 extended ISO range of 40000 through 102400. As you can see, image quality starts to fall off a cliff. Image noise becomes distracting, and the dynamic range drops, leading to a harsher look. But in situations where it makes the difference between getting the shot and not, it might still be tolerable.

Price & Availability of the Sony a6400

Check the current price and availability of the Sony a6400 at:

• Amazon
• B&H Photo
• Adorama
• Camera House (Australia)

It’s available in a few different configurations, ranging from body-only to bundled with either a 16-50mm zoom lens or an 18-135mm zoom lens. You can also find good deals that include a bunch of accessories.

Related: Sony a6400 Memory Card Recommendations

Fixing Image Quality Problems in Editing

The general rule of thumb in photography is that it’s better to get the shot right at the time of capture rather than trying to fix it later. That’s a great aspiration, but it’s not always possible to do if you’re shooting in especially challenging conditions or bumping up against limitations or flaws in gear, conditions, or technique.

But it’s worth mentioning that there are some excellent tools available to help address common image quality issues with digital images. And they’re getting better and better all the time as the power of AI ramps up. They can deal remarkably well with anything from sensor issues like high-ISO image noise to lens issues like distortion, softness, vignetting, and chromatic aberration. (Note: I’m focusing here on corrections related to image quality, not image enhancement tools—that’s a different kettle of fish.)

All-round image processing apps like Lightroom Classic and Capture One have solid tools built in that are very good places to start. But it’s also possible to take it much further with more specialized tools. If you shoot in challenging conditions regularly and find room for improvement in the image quality coming out of the camera, these might well be worth a look (and they have free trials). Some are stand-alone apps; some integrate into image editing suites such as Lightroom Classic.

UPDATE: In April 2023, Adobe released an update to Lightroom Classic that added new AI-powered noise reduction for RAW files. It’s a powerful tool that rivals some of the dedicated apps below. If you’re already using Lightroom Classic for your image editing and organization, it’s well worth trying out—look for the Denoise tool under the Detail panel.

Fixing Image Noise & High ISO Artifacts

• DxO PureRAW 3. Like Lightroom Classic’s Denoise tool, it only works on RAW files. But since was updated to version 3, it has become my go-to app for this kind of thing. I’m consistently amazed at how it can rescue photos with otherwise dodgy image quality from noise. It can also help with lens distortion, lens vignetting, and lens softness.
• DxO DeepPrime. This is the noise-only offering using the same denoising technology as PureRAW.
• Topaz Labs’ DeNoise AI. This is another excellent option for specialized denoising. It works alongside Lightroom or as a standalone app.

Fixing Lens-Related Optical Issues

• DxO PureRAW. Again offers an impressive suite of automatic fixes that are applied before you start editing the images.
• DxO ViewPoint. Correcting for lens distortion and geometry skews. Lightroom Classic and Capture One also have excellent built-in tools for this.
• Topaz Labs Sharpen AI. In addition to standard unsharp tools, it includes focus correction and shake reduction.

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