Striped Lights on Phone Camera? - Advice Wanted

[MoonglowMinis]

So my digital camera has been loaned out to my younger brother. This has left me with only my phone to photograph minis.

 

While playing around with a new lighting setup, I got this stripping effect.

 

 

These aren't present to the naked eye. They only appear in-camera and in the photo. They also "roll" from bottom to top.

 

My guess is it has something to do with the sensor and the lighting but even after eliminating some lights and not others it was still present when photographing a mini on my backdrop.

 

Who's smarter than me and can explain what's happening and how I can prevent it?

[Cicciopiu]

Lamps operating on electric systems produce light flickering at a frequency of twice the power line frequency (50HZ in Europe, I guess 60 in USA?).
To avoid flickering you have to set your shutter speed in multiples of that cycles: so in my country it's 50,100,150 and so on; in USA should be 60,120,180 and so on.
I don't even know if it can be done on a smartphone...

Edited December 21, 2021 by Cicciopiu
grammar -.-

[ManvsMini]

What type of bulbs are you using? I had that problem on my phone with halogen bulbs (came with the flip up hobby lights). Can't remember if CFLs did it too, but once I swapped to LED bulbs it stopped. And as mentioned above, it is caused by interference due to frequency of the light and the shutter-speed.

[haldir]

I recall doing a sampler shot when I picked up Green Stuff World's pop up photo booth. It's similar to the one Reaper offered for RVE earlier this year. It has LEDs for lights & using my cell phone's camera I got these bands as well, so I'll be interested in the solution to these as well.

[Cranky Dog]

The only information I could find is among the same lines. The cameras electronic shutter speed is in sync with the lighting's frequency.

 

I know that webcams often have advanced settings to reduce flickering/banding by taking the localized power frequency into account (i.e. 50hz in Europe, 60hz in North America).

 

For a digital camera, either you'd have to play with the shutter speed (1/60th to anything else), find a different primary source of illumination, or some other setting.

[Cygnwulf]

Pretty much been covered - Light flicker isn't in sync with your capture speed (on a phone there's no shutter but basically the same thing.)

The reason it rolls can be explained because a digital photo sensor captures the information sequentially. So it starts in one corner and polls each sensor in sequence across and down.  As it goes, the hyper fast flicker of the lights, normally invisible to organic sensors like your eye, results in different illumination levels as different portions of the image are captured.  you see multiple bars because the flickers are happening fast enough to go through a couple as your sensor goes through it's capture.

As has been stated, within the camera you can try to find a way to shorten the capture to be the same as the flicker rate (Easily done on a digital camera but maybe/maybe not on a cell phone capture) so the entire capture happens during one cycle, or slowing the capture to the point where a LOT of cycles happen during the capture to even out the levels.  You may not be able to do this at all with your stock phone camera software but sometimes aftermarket camera apps let you get more manual in your settings, and you could lower your sensitivity (ISO) to increase the capture time.  Or if your phone software has a 'night mode' that takes several images and stacks them, that would most likely work around this as well.

 

DSLR cameras don't notice this as much because of how they capture - the shutter opens, all of the pixels are active the whole time, then the shutter closes and THEN the software polls each pixel, so the active time on each pixel all saw the same number of cycles regardless.

 

[MoonglowMinis]

Thanks everyone. I'll see if my phone will let me manually adjust anything, but it's pretty dumb for a smartphone. I thankfully have my dslr back so I shouldn't have to struggle with it.

To answer questions, I have a few different LED bulbs for lighting, though the room behind me is lit with either a CFL or Halogen (not sure, haven't checked and they came with the house)  I'd be surprised if that light was causing it since it casts considerably less light than the LEDs, but who knows.

It's possible my phone was just giving me incompatible settings during that moment - as that's the only time i've seen that.

But thanks for all the responses!

[Cygnwulf]

yeah, LED bulbs can strobe too, particularly if there's a dimmer on them.  LED's don't really have 'brightness' on them, the hack to dim them is to strobe them really fast, and the more time they're off the dimmer they appear.

CFL would definitely strobe. Halogen less so, they function more like an incandescent.