Q S I 5 0 0 S E R I E S U S E R G U I D E
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taken with the CCD at the same temperature as your light frames. If you’re taking LRBG or
other filtered images, ideally you should take a set of flat fields through each filter.
Setup your telescope and possibly your light box to take your preferred style of flats. Adjust
I
with
ould take at least as many flat frames as the light frames you took
through each filter. Taking additional flat fields will produce a master flat with less noise,
lity images. Do not change your focus. To get correct flat fields, it is
Flat Darks
t-
n in MaxIm LE. For complete instructions on calibrating
images, please see the online help in MaxIm LE.
e.
tructions on
images.
the exposure so the average pixel is filled to approximately half its full well depth. With QS
500 Series cameras you should strive for pixel values of roughly 30,000 ADUs. As
dark frames, you sh
yielding higher qua
important that the focus be identical to the focus used for the light frames.
As with any exposure using a CCD camera, dark current builds up while taking a flat field
image therefore the dark current must be subtracted with a dark frame taken at the same
exposure as the flat field. Taking flat-darks is easier and less time consuming than regular
dark frames because the exposure time of flat field images is typically much shorter than
your light frames. If you take flat field images, it is critical that you also take a series of fla
darks. They’re easy to take with the shorter exposure, so take at least 15 flat-darks.
Manual Image Calibration
MaxIm LE supports both automatic and manual image calibration. This section describes
basic manual image calibratio
Subtract Dark Frames
Begin by creating a master Dark Frame for each exposure length. A master dark frame is
created by combining all the individual dark frames using an average or median combin
See the section below
Combine Frames in MaxIm LE
for detailed ins
combining multiple
Tip:
In general, an average combine of multiple images will yield a combined
image with slightly less noise than a median combine, but this requires that none
of the frames being combined have any anomalous groups of light or dark
pixels caused by, for instance, cosmic rays.
Other programs, such as MaxIm DL, include additional combine methods that
attempt to provide the low noise of an average combine with the anomalous
pixel rejection of a median combine. You will need to experiment to achieve
the best results.