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Light and Dark 2x2 Modes
For added convenience and versatility, the SSDSMI-2’s individual pixels
(light-detecting sites) can be “binned” into units of two-by-two pixels (i.e. four
individual pixels create one binned 2x2 pixel). This creates larger and more
sensitive pixels, but with decreased resolution. This can be useful for some
types of astronomical imaging, such as capturing faint nebulae. It can also be
useful for quick-checking the aiming of the telescope or framing of objects
within the field of view of the camera before using the normal Light 1x1 mode
to actually capture images.
To use in “2x2” mode, select Light 2x2 mode for capturing “light” images, and
Dark 2x2 mode to capture dark frames for averaging and subtracting. Images
can be combined and processed in the same way as Light 1x1 images.
Color Filter Imaging Using the SSDSMI-2
To obtain a color image with the SSDSMI-2, you will need to photograph
though a series of filters. While this takes comparatively longer to do than
using a one-shot color camera, the monochrome SSDSMI-2 provides higher
sensitivity to better capture faint deep sky objects. The color definition and
detail is also greater through the use of filters. This method of imaging is used
by professional astronomers to render the most detail and information in their
astrophotos. The most common method for color filter imaging is to use a
Luminance filter, and a Red, Green and Blue filter (LRGB). To better manage
the use of multiple filters, a color filter wheel (available from Orion) is recom-
mended.
The luminance filter is responsible for all of the detail in the image. Providing
ample exposure time and stacking several images with the luminance filter will
be beneficial to your final image. You do not need to use the same exposure
time for all the LRGB channels. Typically, the luminance filter should have the
longest exposure.
The Red, Green, and Blue filters need to be individually photographed through
to later combine a full color image (see “Combine Color”). The color response
of the SSDSMI-2 is generally less sensitive in blue, so that filter may require
slightly more exposure time. For example, if you set a 180 second exposure for
the red and green filters, you may choose an exposure time of 240 seconds for
blue. You will determine what the ultimate color balance should look like, so
some experimentation with the exposure times in each filter may be needed.
Saving your Images for LRGB Imaging
It is a good practice to setup a common naming convention for your images
before combining them and assigning the LRGB colors. If you don’t give unique
names to the images saved with the individual LRGB filters, you will have no
way of knowing which images were taken with each filter. For example, if the
object your are photographing is the Orion Nebula, then you can make the
Base filename for each filtered image to “OrionNebula1L” for Luminance,
“OrionNebula1R” for Red, “OrionNebula1G” for Green, and “OrionNebula1B”