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ing, or sequence shots to be saved automatically in a chosen
directory.
Scrolling down further along the left side, you'll find windows
for other camera attributes including bit depth (always choose
the highest bit depth to get the most detail and quality out of
the image), binning control (1x1 is full camera resolution),
histogram, and cooler control. There are other windows pres-
ent, but the ones listed above are the most important ones
when taking your first image. Some windows are not appli-
cable to astro-imaging, and can be shut off by going into the
Options>preferences menu.
To take your first image, focus must be achieved. With a CMOS
camera, one of the quickest and easiest ways to focus is to
point the camera at a bright star, and choose a fast video frame
rate with higher gain settings so you can watch the star in real
time, and focus until the star becomes a point.
Focusing
1.
Make sure the camera is in preview mode – if not, click the
camera name in the top left window, to turn on streaming
preview mode.
2.
In the Capture and Resolution window (Figure 5), set
the resolution to full, the gain to somewhere in the
middle of the slider, and the exposure to video mode
with "auto exposure" unchecked, and an exposure time
to somewhere around 200-500 milliseconds. This should
provide you with several frames per second, enough to
see a real time focus preview.
3.
This should be good enough to see a bright star like
Vega, provided it's in the field of view, and relatively close
to focus. If you see nothing, but are sure the star is in the
center of the field, adjust your focus in and out because
a very out of focus star will spread out and become quite
dim.
4.
Once you acquire the star, center it, and focus until it
looks like a tiny point. At this point you are probably over
exposing the star, and can back off on the exposure
time and gain settings. If the star is in the middle of the
field, you can also reduce the resolution setting on the
chip, in order to speed up the frame rate, to get a super
responsive live focus. Readjust focus until the star is as
tiny as possible. At this point, everything including the
moon and a distant galaxy will be in focus.
5.
If you wish to fine tune the focus further, a Bahtinov mask
is an ideal method of focusing with Orion StarShoot
Capture, as it is quite an accurate method using medium
brightness stars. Contact Orion or search for Bahtinov
mask on www.telescope.com for more details, and to
purchase a Bahtinov mask for your specific telescope.
Your First Lunar/Planetary Image
The moon is perhaps the easiest object to get your first image,
as it is very bright, and easy to find. Planets are also easier than
nebulae to capture, since you'll be streaming a video file, and
can use programs such as Registax to process the video file.
1.
Go to the Options menu, click preferences, and under
the Record heading, choose a directory location for your
6
saved files, naming convention of your choice, and make
sure the file type is set to AVI.
2.
In the Capture and Resolution window pane, check Video
Mode, uncheck auto exposure, and use the Exposure
Time slider to find an exposure that looks good. Planets
do well with lots of short exposures, so if the exposure
time is too long, experiment with raising the gain, and
lowering the exposure value. It will be more noisy, but the
frame rate will be higher, and the exposure time will be
lower.
3.
When ready to record, press the record button and press
it again when your video is the desired length. In the
Options menu, under Record preferences, you can set
limits to time of the video, as well as number of frames.
4.
You can then load your AVI file into a 3rd party program
such as RegiStax, in order to process the lunar or
planetary details present in the video file.
Auto Exposure can be used if desired, but manually adjusting
the exposure values provides the best control over the image.
Check the "Auto Exposure box, and drag the box over an area
you wish the system to measure. You can resize the box accord-
ingly. Then set the Exposure Target, and the system will try to
keep the exposure close to that target exposure value by adjust-
ing the exposure time automatically.
Your First Deep Sky Image
1.
Now that you're focused, slew to an object you wish to
take a picture of, and the exposure and gain settings will
Figure 6a. Live histogram with "humps" in the normal range
(left of center) for a target deep sky exposure
Figure 6b. Histogram window showing the screenstretch
adjustment bars
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