Dark Frames
is a useful feature for if you’re taking
exposures longer than 1 second
.
Longer exposures and temperature can create noise in your LPI camera called dark current
artifacts. The Dark Frames feature allows you to subtract out some of this noise from your pictures.
Perform the Dark Frames features at night. If the temperature changes significantly during your observing
session, you should repeat this procedure.
To perform the dark Frames procedure:
1.
Select “Take Dark” in the Object type combo box (10). The Dark Frame
Exposure controls display.
2.
Select a range of exposure time. For example, if the length of your exposures
will be between 2 and 5 seconds, set the First Exp (Exposure) box for 2
seconds and the Last Exp box for 5 seconds. The LPI program will then take a
series of dark frames image files between 2 seconds and 5 seconds in length at approximately 0.5 f/stop
intervals (about 1.4 seconds apart). Later, when you set your camera exposure time (see Step 6 below), the
LPI program will automatically select the Dark Frame file with the closest exposure length, scale it to the
actual exposure time and apply it to the image you are taking. In effect, it subtracts out the dark current
artifacts.
more....
Dark Frames
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