6

In an image of a compact fluorescent light bulb, I couldn't figure out the reason for the formation of light and dark bands sort of thing in the image. The same thing happens when I try taking a picture of my CRT TV.

What is the reason for it?

CFL Image

6

As you are taking this on a phone - it has no shutter, instead it scans the CCD matrix (i think top to bottom) to build an image. What you are seeing is the variation in the brightness of the CFL as the camera scans the CCD. these lamps have a running frequency of around 50-60 Hz, as does the picture on your CRT tv (scan frequency).

| improve this answer | |
  • :Thank you for your response.May you elaborate a bit or refer to some resource regarding the scanning process. I could not get a grasp of what scans the CCD. – WhizKid Jun 22 '12 at 20:53
  • Yes: en.wikipedia.org/wiki/Charge-coupled_device its quite complicated, but the ccd type is "interline" and essentially it reads a row at a time to an array. – Digital Lightcraft Jun 23 '12 at 7:33
1

AS the CFL has a flickering luminosity with frequency based on the input current (50/60 Hz or a multiple of this value) you may have some effect due to the interaction with the shutter. Try to set your camera in speed priority mode and push the speed up.

| improve this answer | |

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.