Floating black bands in low light on control station monitor and photographs

[Frostfrog]

Lately I have been taking some after dark, low light pictures of trains with holiday lights. I see rising black bands on my monitor. These bands also show up on my still photographs, particularly at higher shutter speeds and basically disappear at 1/120 of a second, but I need 1/400 to stop train action. I have shot and attached an AEB burst of five images at these shutter speeds to illustrate the problem:

1 1/400 f 3.2
2 1/640 F 3.2
3 1/240 3.3
4 1/1000 f3.2
5 1/160 f 3.2

Has anyone else encountered this? If so, have you found a solution?
Thank you.

 

[Kilrah]

The lights are simply not on steadily but blinking fast like most lights are nowadays.
No solution other than using a slow enough shutter speed to catch them all on in the same frame (for stills) / try different shutter speeds and hope to find one where the scanning of the LEDs somewhat matches the scanning of the sensor (for video).
Or merge the exposures in post...

 

[Frostfrog]

Thank you, Kilrah. I'm aware of this phenomena but am convinced there is more than this happening here. I have photographed these same ornaments with my Canons. Lights captured at the moment they blink off are dark in distinct segments along individual ornaments. In these shots, there are dark banks that extend all the way across the screen and the individual ornaments. They float from bottom to top. Yes, I have been doing as you suggest regarding the merging. It is a time consuming process I would rather avoid if possible. Again, I thank you for your time and thoughts.

 

[EsaT]

Electronic shutter scans image horizontal line at time as rule in CMOS sensors meaning different lines are literally captured at different time.
That phenomenon is called as rolling shutter usually visible as skewing of horizontally moving objcts in frame.

With non-steady light sources that causes some kind usually moving horizontal stripes into picture as rule.

And very little artificial lights are stable brightness lights.
Directly mains powered lights flicker at double the AC frequency.
And in case of brightness control it usually works similar to PWM lowering time light is on making flicker more easily visible.

Similarly brightness control of DC powered lights nowadays works by PWM chopping of voltage at some frequency.
Because of higher power losses with analog linear regulator voltage control, digital PWM has replaced that as rule.
(step down SMPS with output filtering could avoid flickering, but has higher cost)

So pretty certain what you're seeing is combination of rolling shutter and artificial light sources.