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Photo Forum / General Photo Topics / Australian Photography / January 2007red spots on long exopsure
Hi there, some time ago I did a long exposure (45minutes)of star trails with an EOS 300D. Among the noise, were several red dots. I was surprised to see a simmilar effeft recently on a 400d..... anyone got any ideas what the cause of this is? overly excited pixel perhaps? Supernova?? Expolisions from a space battle. It seems ot me more than coincidence that it is red... my impression is that red pixels are more easily excited. in the instance of the 300D it was interesting to note the occurences of the red dots seemed to increase closer to the equatorial pole.... or apparent axis of the stars (or Earth more specifically).... further from the pole, there were less if any. I would also be interested to know if this same effect can be expected on a Infra-red converted camera. kosh > Hi there, > [quoted text clipped - 17 lines] > > kosh oh... and the example on the 400d was using noise reduction for the long exposure..... kosh again >> Hi there, >> [quoted text clipped - 22 lines] > > kosh again Hot pixels on the sensor. Normal during long exposures. >>> Hi there, >>> [quoted text clipped - 25 lines] > Hot pixels on the sensor. > Normal during long exposures. that's what I was thinnking...... but, there must be a way of reducing it, and I am uncertain as to why it would be worse in some spots than others >>> oh... and the example on the 400d was using noise reduction for the >>> long exposure..... [quoted text clipped - 7 lines] > it, and I am uncertain as to why it would be worse in some spots than > others You can Take it to Canon and they will map out the pixels that get that way. It really isn't an issue it's just a quirk of the sensor. Best time to take a long shot in the dark is if you haven't used the camera for an hour or so. >>>> oh... and the example on the 400d was using noise reduction for the >>>> long exposure..... [quoted text clipped - 13 lines] > Best time to take a long shot in the dark is if you haven't used the > camera for an hour or so. are you saying this lessens the effect of hot pixels if they have been through a recent long exposure, or are you saying it is a long shot in the dark ;) kosh >>>>> oh... and the example on the 400d was using noise reduction for the >>>>> long exposure..... [quoted text clipped - 19 lines] > > kosh both ;) >Hi there, Doesn't a red spot on a picture traditionally indicate that it's been sold (sorry).....? > >Hi there, > > Doesn't a red spot on a picture traditionally indicate that it's been sold > (sorry).....? Oh by the way David, I developed some red spots after our relationship. I suggest you go to the clinic asap. >>Hi there, > > Doesn't a red spot on a picture traditionally indicate that it's been sold > (sorry).....? I thought it meant it was on special! |
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