I have a D200 which works fine in "normal" circumstances. However I tried to do a long night exposure--about 3 minutes--and found that the top sides and bottom middle of the frame were "washed out" with pink flare--looking almost like light-struck film. Further tests showed that this was always in the same place, appearing at about 1 minute exposure, and growing in strength and size as the exposure time increased. Is this normal? I have seen digital pix done with very long exposures that looked fine. I'm running to the end of my warranty--should this be brought back to Nikon? TIA for any advice, Toby
Did you enable the dark frame subtraction? Effects at the edges are, I understand, to the sensor becoming warm and the dark current increasing. Dark frame subtraction may reduce the effect of the abnormally high dark current, although it doubles the exposure time, presumably making the sensor even warmer.... David
At what ISO? If it does this at ISO 100, it's strange. Mine only starts showing some of this around 10-15min at ISO 100. With dark frame subtraction, I have exposures at several minutes at ISO 800 which do not show this problem. In short, switch on DFS (ie "Long exp NR") to get rid of this. You do pay a price in time, though.
You have answered my question. I was exposing at ISO 1600, so I imagine that it is quite normal for the "purple haze" to appear after 3 mins at that high setting. Many thanks to all for taking the time to enlighten me. Cheers, Toby