I just bought a cheap action-camera and start experimenting with RAW format. The output file has some defective pixels. I know that they can be "removed", but it seems to me that they are too many. I would like to know if this is normal or not. See here a test image (10 seconds exposure). And a second one (automatic exposure, cap on).

The sensor is Sony IMX078.

Thank you.

  • When working with long exposures, hot pixels are common
    – Janardan S
    Feb 22 '17 at 17:43
  • @Janas You mean the number is increasing with exposure? Feb 22 '17 at 17:52
  • What camera are you using? If it's a low-quality camera, then perhaps lots of hot pixels is common.
    – scottbb
    Feb 22 '17 at 18:08
  • 4
    Those look like hot pixels, not stuck pixels. They're normal for longer exposures on all sensors. There's a process called dark frame removal that is often used automatically in cameras to remove them on long exposures.
    – StephenG
    Feb 22 '17 at 21:17
  • 1
    It's not a defect. It's quite normal - the best DSLRs have these issues in long exposures.
    – StephenG
    Feb 23 '17 at 15:43

With any image sensor you will get some hot pixels and these will be noticeable in long exposures - but easily fixed in post processing. Unfortunately what is a 'normal' amount is very subjective, most sensor manufacturers do mention a percentage of pixels that may or may not work as no manufacturing process is 100% perfect, the more well known manufacturers Sony, Canon etc will have higher quality control than less known or knock off brands.

1) You may have an older / cheaper Sony sensor in your camera that may have a few dodgy pixels 2) You could have a dodgy camera

If you are concerned and the camera is within warranty have a chat with the manufacturer and you may get it replaced or repaired.

  • Do you have an opinion on the posted image? Normal, too many? Feb 22 '17 at 20:20
  • Well personally, if I didnt pay too much for the camera I would keep an eye on the issue and if it didnt get any worse then I'd live with it. However if I'd paid a reasonable amount I'd personally contact the manufacturer. The old 'you get what you paid for' may apply here :)
    – LMP2016
    Feb 22 '17 at 20:40
  • I didn't have high expectations from camera; I was surprised to see so many defective pixels from a Sony sensor. Thank you. Feb 22 '17 at 20:51
  • To get a feeling of how many in total there might be, you could find something pure black like a sheet and do a long exposure, this way there will be no distractions in the image and you can better make the call on whether to return the camera or not
    – LMP2016
    Feb 22 '17 at 20:58

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.