Explanation for green spot and Fluorecent lighting

Discussion in 'iPhone' started by wvphysics, Jul 7, 2010.

  1. wvphysics macrumors regular

    Jul 7, 2010
    I've been combing through forum posts for a few days and cannot find an explanation for the green spot issue other than it occurs under fluorescent lighting. At work I get the greent spot, at home under CFLs I get the green spot AND the white balance issue of yellow pictures. Has anyone com across an explanation why fluorescents do this. I am trying to give apple time to put out the software update to see if they fix the white balance issue, but even then since I can't figure out what causes the green spot I can't figure out if a software update would even work. My best guess is maybe the sensor needs recalibrated, but again no real idea.
    If theres no fix by next week I guess I'll have to ship it back since I got it online. Brings me to my second question, anyone get one of these magical black box iphone 4 replacements, that magically work like they are supposed to, from an online replacement or are they only from in-store replacements?
  2. Givmeabrek macrumors 68040


    Apr 20, 2009
    I assume you have read this thread:


    All cameras have a problem with fluorescent lighting. Especially cameras that don't let you control white balance and shutter speed. The lighting is changing 120 times per second (twice per cycle). In low light the shutter speed is probably below 120. This will cause uneven lighting in the image.

    With a mechanical shutter you you will see a bar or half an image affected, even on a professional camera like my Canon 5D2 the result is the same. With an iPhone that has an electronic shutter the result is more unpredictable. You see a blob in the image. There is no quick fix. Change the lighting by using the flash, turning on more incandescent light etc. Post processing can help with white balance issues.

    Adding some control of shutter speed and a basic white balance control would be a big help. :)
  3. Rooftop voter macrumors 6502a

    Jan 26, 2010
    Do all the phones have the green spots problem? I just noticed this on my new "black box replacement" phone. Never noticed it on my other one, then again I wasn't looking. It only seems to happen when in a poor light situation photographing a white background.
  4. bobright macrumors 601

    Jun 29, 2010
    I had this issue, until I realized it was my shield all slong slightly misplaced a centimeter or so causing it. Haha.
  5. wvphysics thread starter macrumors regular

    Jul 7, 2010
    I have read that post. As I stated in my original post I am looking for why the 120 Hz cycling would cause a green discoloration as a circle in the middle of the screen. For something that is supposed to be "unpredictible", it sure seems easy to predict that it shows up as a circle in the middle of the screen for all the photos people have posted. Do iPhones even have a shutter? Optical sensors can work by changing the length of time the sensor builds charge from photons before discharging and measuring to record intensity (the exposure time). I would imagine a longer exposure time than the timing of the fluorescent would help even out lighting in the picture.
    So does anyone have an explanation beyond just saying it's tge 120 Hz and shutter speed?

Share This Page