Nikon Z8 Pixel Shift Shooting to Reduce Aliasing

The highest frequency you can accurately capture in a photo is called the Nyquist frequency, no matter how good your lens is. If you take a picture of finely-spaced details that are smaller than twice your camera sensor’s pixel spacing, you’ll get that ugly aliasing. In other words, your sensor needs at least two pixels across for every skinny line in a light-dark pattern to properly record them.

Aliasing is often called ‘false detail’. With this defect, you can get weird color rainbows where none exist and also light/dark patterns where there shouldn’t be any.

In the past, the only way to get rid of aliasing was to either buy a camera with more pixels or to fuzz-out the image using a camera that had an anti-aliasing sensor filter. Neither option is very good, unless you have plenty of disposable income for that huge medium-format camera.

Several camera companies, now including Nikon, let you perform pixel-shift shooting. With this technology, your camera can rapidly move (shift) your camera sensor by typically half or a full pixel width both horizontally and vertically. After moving the sensor, the camera takes another photo and then repeats the process with each neighboring pixel. After the fact, you can use an editor to combine these shots into a single photograph that has effectively more pixels in it.

If you haven’t already figured it out, this means that you can’t use pixel-shift shooting for moving targets.

The Nikon Z8 (plus the Nikon Zf and Z6III) support pixel-shift shooting. You can take 4,8,16 or 32 shots and then combine them using Nikon’s NX Studio.  I made an article about how this process works located here. 

You can now get pictures with up to 16512 X 11008 pixels, or 181MP, if you choose the 16 or 32-shot options. I noted that the combined shots are 912MB (in NEFX form). I shoot in the raw ‘HE’ format, to get smaller raw files. When I used the free Adobe DNG Converter, these shots were reduced to 559MB. Still huge.

Everybody talks about the pixel-shift shooting benefits of higher resolution and image noise reduction, but the ability to reduce or eliminate aliasing has been largely ignored.

70mm 1/320s f/4 ISO 5000, 200% zoom view, single shot

The shot above was taken from the 1st capture out of the 32-shot sequence that created a pixel-shifted picture. I shot at a distance that clearly shows aliasing (see the barcode above). It’s easy to see the blue and orange colors inside the barcode that didn’t exist in real life. The screen capture here is at 200% zoom from a much larger image.

As an aside, note that there’s a fair amount of image noise and much of the text is illegible. I did a 32-shot pixel-shift sequence to show the limits of what this camera could do to rid noise, increase resolution, and of course attempt to rid aliasing.

70mm 1/320s f/4 ISO 5000, 100% zoom view, merged 32-shot

The merged 32 pixel-shifted shots make a world of difference. Besides the obvious resolution increase and image noise elimination, note that the barcode was transformed from false orange/blue mush into distinct lines.

Horrible aliasing and noise, single shot

NO aliasing and no noise, 32-shot pixel-shift merge.

As seen above, the standard Nikon Z8 sensor resolution resulted in a shot where black lines in the barcode were replaced by fake orange and blue rainbows. This effect can really make some fabrics look horrific, too.

All of the shots shown were processed in Capture One 2023 with no sharpening or noise reduction. If I were to process the merged shot with my Topaz DeNoise AI, it could be made even sharper than what you see here.

I used my Sigma Sports 70-200 f/2.8 zoom for all of the shots in this article. This is a really sharp lens, and it’s obviously capable of producing much higher resolution than my Z8 sensor can use. If you notice that your photographs have aliasing in them, it’s a dead giveaway that your lens resolution is better than your camera sensor.

As you can see, going from a sensor with 5520 X 8280 pixels to an effective sensor with 11008 X 16512 pixels is an enormous jump in quality that has to be seen to be appreciated. It’s just a shame that you can’t do this with action shots.

While it’s impossible to rid aliasing in all situations, this technique will get rid of it for the vast majority of cases.

I’m still waiting somewhat impatiently for this feature to show up on my Nikon Z9 with the next firmware update…