This is one in a series of posts on the Nikon Z7. You should be able to find all the posts about that camera in the Category List on the right sidebar, below the Articles widget. There’s a drop-down menu there that you can use to get to all the posts in this series; just look for “Nikon Z6/7”.
I reported here that the Z7 scans at about 1/16 second when using the silent shutter. This can cause horizontal bands (in landscape orientation) when the subject is lit by lights that change intensity during the exposure. Many fluorescents and light-emitting diode (LED) lights do that. The lights that are today replacing the nice, steady incandescent illumination typically have variations at twice the line (or mains, if you speak British) frequency. In the US, that’s 60 Hz, so the cycle of the lighting is usually at 120 Hz. In Europe and Britain, the mains frequency is 50 Hz, and the lighting flickers at 100 Hz.
Not all LEDs flicker. The ones that are made for photography usually show no noticeable flicker, or flicker at frequencies well above the power line frequency. Modern LED stage lighting often flickers at frequencies unrelated to the power line.
In the olden days of film photography and cathode ray tubes (CRTs), we sometimes had to get a picture of, say, a TV set in out images. If we weren’t careful, the scanning of the CRT would be visible in the photograph, which was usually unwanted. Since the CRT was scanned at a frequency close to, but not the same as, the mains frequency, the conventional wisdom was to set the camera shutter speed to one or two power line cycles so that every place one the screen had a chance to go through an integral number of scans. In the US, the magic shutter speeds were 1/60 and 1/30 second, and in Europe they were 1/50 and 1/25 second. In practice, this sort of worked. The shutters of the day were not sufficiently accurate for a perfect fix.
I photographed a LED-illuminated light fixture with the Nikon Z7 and the 24-70 Nikkor S lens at various shutter speeds. I developed the images in Lightroom, performing white balance to taste and adding a Clarity move to emphasize the banding. I live in the US, so the magic shutter speeds should be 1/125, 1/60, and 1/30 second. As you’ll see, they all work fine. In addition, the effect diminishes at the shutter speeds get longer.
Here are the images:
This one is fine.
Pretty darned good.