The camera in question is a Canon A470.
Last night I set up a sunset script (sunset5.bas as I recall) which is very good at night photography btw, and pointed my camera at Polaris. I did as continuous an exposure as possible. There was 1 second between shots, and after each exposure it took several seconds for the images to save to the SD card. Between the exposures, saving, and the 1 second delay I got about 4 shots per minute. After about 45 minutes of this, the images started getting noisy. Also, the file size started getting bigger, probably due to the noise in the image. At 7.1mp, they started at 1mb per, and ended up at almost 3mb per image after a couple of hours, with a LOT of noise in the image.
Looking at the meta data in the pix in Picasa, the exposure was 15s on all the noisier pictures but between 8 and 13 seconds on the less noisy ones. ISO and everything else was the same. The only thing I can think of is that the CCD sensor is getting overheated and introducing noise. I've posted samples of each here:
https://plus.google.com/photos/109190891124377551497/albums/5874599449734535745?authkey=COqqp4fR-bvUvAEThanks for any input on how to minimize or solve this problem. Maybe I just need to give it 15-30 seconds between exposures to cool down. The ambient temperature last night was fairly cool (not cold).
