Handbook for the TRIUS PRO 694 Issue 19th April 2019
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Starlight Vision has a focus routine that will repeatedly download and display a 128 x
128 pixel segment of the image at relatively high speed. This focus window may be
positioned anywhere in the camera field. To use this mode, start up the software
and select the Exposure mode. Set the camera mode to Binned 1x1 and select an
exposure time of 1 second. Press ‘Start Exposure’ and wait for the image to
download. There is a good chance that a suitable star will appear somewhere within
the image frame. Now go to the ‘Focus’ tab and press ‘Get focus object’ - you can
now click on a suitable star in your main image and its co-ordinates will be shown.
Now click ‘Run focus exposure’ and you will see a steady stream of star images in the
focus window. adjust the focusing of your telescope to get the sharpest definition.
Once you are happy with the focus quality achieved, you might like to trim the
settings of your par-focal or flip mirror eyepiece to match the current camera
position.
Although you can reach a good focus by the above method, many observers prefer
to use additional aids, such as Hartmann or Bahnitov masks (an objective cover with
several spaced holes) or diffraction bars (narrow parallel rods across the telescope
aperture). These make the point of precise focus easier to determine by creating
‘double images’ or bright diffraction spikes around stars, which merge at the setting
of exact focus.
Taking your first astronomical image:
I will assume that you are now set up with a focused camera attached to a telescope
with an operating sidereal drive. If so, you are now in a position to take a moderately
long exposure of some interesting deep-sky astronomical object (I will deal with
planets later). As many sidereal drives are not very accurate beyond a minute or two
of exposure time, I suggest that you find a fairly bright object to image, such as M42,
M13, M27 or M57. There are many others to choose from, but these are good
examples.
Use the finder to align on your chosen object and then centre it accurately. Once
properly centred and focused, take an exposure of about 60 seconds, and observe
the result. Initially, the image may appear rather barren and show only a few stars,
however, a great deal of data is hidden from view. You can get to see a lot of this,
without affecting the image data, if you go to the Histogram window and adjust the
two sliders to frame the main peak in the image data. The faint image details will
then appear in good contrast and I think that you will be impressed by the result!
If you are happy with the image, go to the ‘File’ menu and save it as a FITS file in a
convenient directory.
