Studying High ISO and Noise on the Nikon Z5


Nikon Z5, ISO100

High ISO is deteriorating your image, no question about that. I wanted to know, how much. So, I did a short test with several ISO settings. I apply a bit of noise reduction to any image, even to ISO100. These settings are about 10% monochrome and color noise reduction and 50% details. This just flattens the noise in the shadows a bit, and I found no negative impact on the image, even if I sharpened a lot. By the way, the image above is focussed on the eye of the figure.

Of course, you can decide to ignore noise altogether. This works best in black and white. It can give images that old-fashioned grain and a special mood. I have seen artistic landscapes which play with this effect masterfully, even add noise to the image. Grain does also work in color for stage photography. In fact, it may be the best solution, better than to try to smoothen the noise away. You can learn to embrace it and my find the clean images boring after a while.

In this posting, however, we go for another style.

ISO12800, noise removed

Have a close look at the images above and below which used ISO128000, and additionally high noise removal in Lightroom with 100% detail enhancement. In this blog, you can open the images in an image box, but not download the image. Thus, I took a screenshot viewing the images at 100%.

ISO12800, Noise removed, 100%

If you view that crop as large as possible, you can see the damage that the noise and its reduction did to the image. It is important to remember that you will see these problems only in prints. Nobody has a screen which would show these small issues. I think you can easily print with 50-100cm height before you notice them.

ISO100, 100%

For your comparison, above the ISO100 version at 100%. It has none of those concerns and is completely clean. I cropped a bit wider here.

The following is the version at ISO12800, with no noise reduction at all. It clearly shows the noise and the effect it must have on the details of the image. You can see the noise, even without pixel-peeping. Noise reduction smoothens that out, as you saw in the version above, but loses very fine textures, of course.

ISO12800, no noise reduction

The question is, how much ISO is too much? It does depend on the image, of course. The chosen scene does not have very fine details that matter. E.g., a landscape image needs more care, especially if you want to present it in a large print. There is no point in a 45 Megapixel image which is covered by noise sprinkles. It would be better to use a sensor with a lower resolution. These sensors have less noise to start with.

I find that I can go up to ISO1600 on my Nikon Z5 for almost all scenes. For a demonstration, I have the image above at ISO1600, first with the low noise reduction that I apply to all images.

ISO1600, no noise reduction, 100%

This image has a lot of noise, albeit less than ISO12800. You won't notice the noise much in normal screens, even large ones.

ISO1600, no noise reduction

However, it is easy to remove the noise with a bit more noise reduction in Lightroom. I use around 40% for monochrome and color, and 70% details. If you sharpen a lot, make sure that you mask the sharpening. Here is the result.

ISO1600, noise reduced, 100%

Clearly, you might lose some tiny details. The image, again, is not meant to show many fine structures and textures. But ISO1600 works in most scenes quite well. If you have to use it, the image would usually not be an image where the details matter.

Consequently, I have either my AUTO ISO off and only increase it if absolutely necessary, or have a limit of ISO1600 for a "snapshot" setting, e.g. in street photography. The Nikon can set a shutter speed limit, or an automatic shutter speed limit which depends on the focal length with an additional parameter from low to high.

In any case, do not be afraid to use higher ISO if you need a faster shutter speed. It is better to remove some noise than to have a blurry image. And it is not always an option to use an open aperture due to DOF. The built in ISO or VR helps, but cannot prevent motion blur, of course.

ISO1600, 1/15, F8