User guide

Q S I 5 0 0 / 6 0 0 S E R I E S U S E R G U I D E
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If everything was done correctly the calibrated and combined image should show additional
detail with less noise and greater contrast than the individual frames. Changing the range
of displayed brightness levels in Screen Stretch window will show additional detail in
different parts of the raw image file. Save the image with a name that allows you to identify
this image as a combined master image.
MaxIm provides additional tools for manipulating images. Please refer to the online help on
Image Processing in MaxIm for additional details. After performing image calibration in
MaxIm, many astronomers prefer to move the individual or combined image files into Adobe
Photoshop or other dedicated image processing program for further processing.
Binning
Binning allows you to combine multiple pixels into what are effectively larger pixels with up
to sixteen times the surface area and sensitivity as an individual pixel. The standard binning
mode is 1x1 meaning that each logical pixel is equal to one physical pixel. The QSI 500
Series supports symmetrical and asymmetrical binning up to at least 3 pixels in either axis.
Some models offer additional binning options. Larger binning modes like these provide
increased sensitivity and dynamic range at the expense of resolution. Asymmetrical binning
(e.g. 1x3 or 3x2) is not commonly used but can be very useful for specialized applications
such as spectroscopy.
The following image illustrates how rows and columns of pixels are combined when binning an
image. Notice how the effective dimensions of the CCD changes with the degree of binning.
1x1 Binning 2x2 Binning 3x3 Binning
3326x2504 1663x1252 1108x834 QSI 583 image size
Binning other than 1x1 is typically used in two different situations. First, the human eye is
much more sensitive to subtle changes in image brightness than it is to small changes in
color. This can be taken advantage when producing color images by taking luminance
images through the ―L‖ filter binned 1x1 and red, green and blue images binned 2x2. When
combined with the luminance image the 2x2 binned color image is almost indistinguishable
from using 1x1 binning for the color frames.
The second situation where 2x2 or higher binning is used is when seeing conditions don’t
support high resolution imaging. If each pixel on your CCD ―sees‖ 2 arc seconds of the sky
through your telescope and the local seeing conditions are only 4 arc seconds, you won’t
benefit from the increased resolution offered by 1x1 binning. In this case, binning 2x2 will
yield optimal results in a shorter amount of time.