Nikon Z9 Review

High ISO Noise and ISO Invariance

The Nikon Z9 has similar high ISO performance to the other 45-megapixel Nikon sensors. Here’s a complete list of 100% crops (a 640 x 960 pixel excerpt of the image) starting at base ISO 64, then at every full stop from ISO 100 to 102,800. You’ll need to click the images to see the full 640 x 960 crop.

Keep in mind that these are extreme crops. With this performance, I’d be happiest at ISO 6400 and under, but I’d have no problems bumping it to ISO 12,800 from time to time. In a pinch, somewhere between ISO 25,600 and 51,200 remains usable, albeit not at large print sizes.

However, without the context of other cameras, it might be tricky to tell if this is good or bad high ISO performance. So, here’s a comparison against the same-resolution Nikon Z7 (identical in performance to the Z7 II). In all these images, the Nikon Z7 is on the top, and the Nikon Z9 is on the bottom. I’ll start at ISO 1600:

ISO 3200:

ISO 6400:

ISO 12,800:

ISO 25,600:

ISO 51,200:

ISO 102,400:

This is as close to identical performance as two cameras with different sensor designs are likely to be. From ISO 1600 through 12,800, I see no reason to prefer one over the other. At ISO 25,600 specifically, I might be able to fool myself into thinking that the Z9 resolves some details a bit better. At 51,200 and 102,400, they’re both equally mushy mush.

To get any improvements in high ISO performance, your best option is to use a lower resolution sensor, like 24 megapixels rather than 45. Here’s the Nikon Z6 (same ISO performance as the Z6 II) against the Z9, starting at ISO 1600. In this case, to make a fairer comparison, I downsampled the Z9 images upon export to be the same dimensions as those from the Z6, 468 x 702 pixels each. The Z6 is on the top, and the Z9 is on the bottom. Starting with ISO 1600:

ISO 3200:

ISO 6400:

ISO 12,800:

ISO 25,600:

ISO 51,200:

ISO 102,400:

In this case, the Nikon Z6 has less noise and better high ISO performance overall. However, at ISO 6400 and below, I prefer the Nikon Z9 because of its better detail – detail that’s visible even though the images have been downsampled to 24 megapixels. (If you don’t downsample the Z9’s photos, there’s a valid case for preferring the Z9’s file up to about ISO 25,600.)

Overall, while the Nikon Z9 may fall a bit short in low light compared to 24-megapixel sensors, it has very good high ISO performance overall. I have no issues recommending this camera to sports, wildlife, and event photographers who shoot in dark conditions.

ISO Invariance

Many cameras today are close to ISO invariant, which – boiled down – means that increasing ISO in-camera provides a similar level of image quality as brightening the photo in post-processing. On ISO invariant cameras, you maximize your dynamic range in low light situations by being exceedingly cautious about blowing out highlights at high ISO values. For instance, instead of a properly exposed photo at ISO 6400 that has a chance of blowing out highlights, it’s preferable to take a dark photo at ISO 800 or 1600 and brighten it in post-processing, to ensure that highlight detail is retained.

It’s not a beginner topic, but then again, the Nikon Z9 is not a beginner camera. I had seen reports online that the Nikon Z9 has a dual-gain sensor, meaning that there are only two “real” ISO values, and the other ISO values can be replicated very closely by brightening the image in post-processing. Specifically, ISO 500 is reported to be the dual gain point on the Nikon Z9.

To put that to the test, I took a photo at ISO 500 on the Nikon Z9, deliberately underexposed by four stops. I then brightened it in Lightroom to compare head-to-head against a photo at ISO 8000. Here are those results, with a brightened ISO 500 on the top and ISO 8000 on the bottom:

Since the results are nearly interchangeable, it’s clear that ISO 500 and 8000 are invariant. To see if ISO 500 is really the dual gain point, I made a similar test at ISO 400 compared to ISO 6400:

In this case, the results definitely are not interchangeable – which means the internet is telling the truth! The Nikon Z9 is not a fully ISO-invariant camera.

I’ll spare you the the pictures, but I performed the same test at all ISO values and found everything from ISO 64 through 400 could be accurately simulated by brightening ISO 64, and everything from ISO 500 onward could be accurately simulated by brightening ISO 500. As such, the Nikon Z9 has a dual gain sensor that switches at ISO 500.

Note, however, that most post-processing software does not do a good job with extreme brightening. Even on a totally ISO invariant camera, it’s still best practice to limit yourself to about three stops of exposure recovery in post.

What does this mean for actually shooting with the Z9? One approach is to keep the camera at ISO 64 whenever your meter suggests something from ISO 64 to ISO 400; keep it at ISO 500 when the meter suggests anything from ISO 500 to ISO 4000; and use an ISO that’s three stops darker than the meter’s recommendation when anything higher than ISO 4000 is recommended.

Another good way to use the Z9 is just to use it like normal. Expose roughly how the meter says, but make sure to avoid overexposure in the highlights, especially at higher-than-ISO-500 ISOs.

If you don’t blow out any highlights, both approaches will give you the same image quality. I think the second method is the saner of the two, but it’s up to you.

On the next page of this review, I’ll cover the Nikon Z9’s dynamic range characteristics. Click the menu below to go to the following page, “Dynamic Range.”