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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.

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Dark Frames

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Meade LPI Bedienerhandbuch Seite 27