40D white balance

[EiRiK]

tried taking 2 or more pix using multi-shot drive mode
turns out that the white balance is very different for the 2 consecutive shots

pix taken under typical indoor condition, no special lighting, only living room llight.
tried AWB and various other WB modes, also tried M, A, T and P.

is there something wrong with my 40d? coz how come can 2 images taken milliseconds apart produce 2 diff white balance?

also, the right third of my histogram is almost always flat, pix always turn out under.... something wrong too?

thanks ppl

[aloyyolaaloy]

is it fluorescent??
http://photo.net/bboard/q-and-a-fetch-msg?msg_id=00OAnb

if its under.. then your shutter speed could be too high

[J-Chan]

for the pics being underexposed.. were you aiming at a white wall?

[EiRiK]

Originally Posted by aloyyolaaloy is it fluorescent?? http://photo.net/bboard/q-and-a-fetch-msg?msg_id=00OAnb if its under.. then your shutter speed could be too high

thanks for the link, it probably is the fluorescent light, will do more test

dun think its the shutter speed, no such problem when i was shooting wif my old 10d. i have to +0.3 or +0.7 most of the time with the 40d to get a brighter exposure

[EiRiK]

Originally Posted by J-Chan for the pics being underexposed.. were you aiming at a white wall?

nop, just some test shots around my house, standard stuff, furniture, appliances, etc

[calebk]

Originally Posted by EiRiK thanks for the link, it probably is the fluorescent light, will do more test dun think its the shutter speed, no such problem when i was shooting wif my old 10d. i have to +0.3 or +0.7 most of the time with the 40d to get a brighter exposure

I quote, regarding fluorescent tubes:

Quote: they are not contiguous but cycle off/on - reverse their polarity - at 120 cycles/second (in the US, 100 cycles in Europe.) Moreover, most "general purpose" fluorescent bulbs have an incomplete spectrum (a "hole" which results in the death-green color cast...) and that part if very difficult to balance by digital cameras (solution - use custom WB for such shots.) The variable color cast on consecutive frames may result from different exposures (some lights have cycled off between the metring and shutter release) or/and different spectral composition of the light (bulbs age which affects their spectral properties, or there are differnt types of bulbs installed in one room, etc.)

The colour shift you see is most likely due to usage of a certain shutter speed, not so much whether it is a fast one or a slow one (but there is a higher likelihood of encountering it with a fast shutter speed).

The rest of the thread does cover ideal shutter speeds to average the spectrum change so that you are less likely to encounter the colour shift.

[alternatve]

Fluorescent is really a miracle of lighting, as a trainee electrical engineer, you get familiar with it. Unfortunately it isn't as friendly to photographers due to it's often flat lighting and strange reaction stated by calabk. The second generation of fluorescents promises to be better... but we just have to wait and see.

What I do is when I think I have a problem with my camera is to test it at every sort of lighting situation out and indoor and get second opinions so that I know that it's not me that's at fault but the camera. Did that with my 40D and made the decision to send it in the shop. It's still there unfortunately... -_- Something mighty screwed up and it forces the guys at CSC to hold it back another week. Hope they throw in a lens or two for compensation..

Samuel

[kurtlim]

Originally Posted by EiRiK also, the right third of my histogram is almost always flat, pix always turn out under.... something wrong too?

check this thread.

I haven't send mine yet, wonder if coldfish had solved his.