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jbinpg
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| Original Filesize | 1.83 MB | | Category | Night Scene | Original Dimensions | 1544 x 1029 | | Date Posted | 01-19-2009 12:01 AM | Number Of Views | 217 | | Average Rating |  | Number Of Comments | 0 | | Title | Star trails | | Description | The fact that the Dark Frame Subtraction (which lasts as long as the original exposure) cannot be turned off on the K20D is a major PITA. However, at least the DFS does work beautifully. There are no hot pixels in this shot. Ambient temperature was -8C at the beginning of the exposure and -9C at the end. Interestingly, the EXIF data recorded the temperature as +20C so the camera temperature sensor must either be reading off some warm part of the circuit board or it recorded the temperature at the start of the exposure before the camera had started to cool down to ambient temperature. Note the EXIF time recorded was the beginning of the exposure so perhaps most/all EXIF data is derived from the beginning of a shot. The neighbour's dog brushed up against the tripod at the beginning of the exposure which explains the strange curve in the trailing end of the trails (rotation is counter-clockwise here). Polaris is the bright star in the centre, only about 42 seconds from the stellar north pole (the extension of the earth's rotational axis). The faintest star recorded here is about visual magnitude 10 which is surprisingly faint for ISO100. Note that the city of Prince George lies 10 km to the NW (left) of the tripod position which explains the brightening of the sky in that direction. Yes, the camera was on the 120 VAC adapter for both the shot and the DFS. I will be attempting to find darker skies to repeat this. RAW file recorded in PEF format and converted to jpeg format in Ufraw v0.15. Further dark frame subtraction for good luck in Ufraw as well although it didn't need it. | | Camera | K20D | | Lens | FA 50/1.4 @ f2.8, 67.1 minutes, ISO100 | | Location | Prince George, BC, Canada | |
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Night Scene - Star trails
