davidmccracken Posted January 17, 2005 Share Posted January 17, 2005 I recently wanted to try a 'super long exposure' with my Canon EOS 10D. You will see what I was trying to do from the picture along with this posting. The camera settings were ISO 100. f9.5 on a 50mm Canon Macro lens. Exposure time was set to 5 hours and 20 minutes using a TC-80N3 remote control. When I look at the exif the Tv value is given as 6553.5 and NOT 19200 as I would have expected. I was using mains via a Canon ACK-E2 power supply. The photograph was taken in a darkened room with the eye-piece covered and the camera and subject covered with a dark sheet. The only source of light should have been the luminous characters on my watch. I have two questions. 1. Why would the camera shut off after only 6553.5 seconds? 2. I understand the exposure is wrong here but why is the right and bottom of this picture so hot?<div></div> Link to comment Share on other sites More sharing options...
coconutdaydream Posted January 18, 2005 Share Posted January 18, 2005 the sensors generate heat, thus the name "hot pixels." as for the camera shutting off after that amount of time, i have no idea. i would suggest the dark noise calibration technique to reduce noise, it works great. also check around to see if exposures that long will damage the sensor, you can never be too safe. Link to comment Share on other sites More sharing options...
jimh Posted January 18, 2005 Share Posted January 18, 2005 6553.5 sounds too close to 65536 to be a pure coincidence. 65536 is the largest decimal value that can be represented with a 16 bit digital system. My guess is that the camera has a 16 bit timer and can't stay open longer. If it wasn't for the specific value, I would have guessed your batteries just went bad. The hot areas are probably there because of electronics close to the sensor getting hot. Link to comment Share on other sites More sharing options...
davidmccracken Posted January 18, 2005 Author Share Posted January 18, 2005 Joey & Jim, I have checked the camera out. It doesn't switch off after the time mentioned. It shouldn't damage the sensor.... (I hope!) That is what the TC-80N3 is made for. Thank you both! Link to comment Share on other sites More sharing options...
john_baker8 Posted January 19, 2005 Share Posted January 19, 2005 I have seen articles about noise in digital cameras. If I remember correctly there are 3 different types of noise, one of which is thermal. The noise around the edges of the picture is actually comping from the heat of the electronics. Link to comment Share on other sites More sharing options...
davidmccracken Posted January 22, 2005 Author Share Posted January 22, 2005 John, Thanks! Someone kindly directed me to this link for a work around. http://www.photo.net/learn/dark_noise/ Link to comment Share on other sites More sharing options...
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