Bio-Rad EXQuest Spot Cutter - Manual (Page 522)

Appendix K. VersaDoc
K-15
exposures. In most cases, you will want to subtract this dark current from your
images.
The settings for subtracting the dark current are in the Options dialog box. Click on
the Options button in the acquisition window to open this dialog.
Normal
The Normal option button selects the default dark subtraction type. In this mode, after
you acquire an image, a “dark” image of the same exposure length will be taken, and
this will be subtracted from your image.
The progress of the dark exposure will be displayed in the Exposure Status bar
following the regular image exposure.
In Normal mode, a dark image is only acquired the first time you perform a scan with
particular application and exposure settings. If you perform subsequent scans with the
same settings, no dark exposure will be taken.
Reference
If you do not want to perform a dark exposure with each acquisition, you can take a
“reference” dark exposure that will be saved and subtracted from all subsequent
acquisitions. Click on the Referenced button to activate this feature.
The first time you acquire an image after selecting this option, the VersaDoc will take
a dark exposure that will be saved and used to subtract the dark current from all
subsequent acquisitions.
Note: The VersaDoc 1000 will take a 60-second reference dark exposure; the VersaDoc
3000 and 5000 will take a 180-second reference dark exposure.
For image exposures that are longer or shorter than the reference dark, the reference
dark will be scaled accordingly and then subtracted. It is recommended that the
reference dark exposure time be equal to or greater than the sample exposure time.
You can change the default reference dark exposure time using the Reset Reference
button (see below).
If you deselect the Referenced button and then reselect it, the old reference dark
exposure will still be available.