Focusing The Ccd Camera - Santa Barbara Instrument Group STL-1001E Operating Manual

up, or the USB port has not yet been properly selected, a message will be displayed indicating
that the software failed to establish a link to the camera. If this happens, use the
Communications Setup command in the Misc menu to configure the CCDOPS software for the
USB. Then use the Establish COM Link command in the Camera Menu to establish
communications with the camera.
Note: It is not necessary to have a camera connected to your computer to run the software and
display images already saved onto disk. It is only necessary to have a camera connected
when you take new images.
Once the COM link has been established you may need to set the camera's setpoint temperature
in the Camera Setup command. The Research Series cameras power up regulating to whatever
temperature the CCD is at, which in this case will be the ambient temperature. Use the Camera
Setup command and choose a setpoint temperature approximately 30°C below the ambient
temperature. Type in the setpoint, set the temperature control to active, and hit ENTER.
Another way to set the camera for the lowest temperature for a given night is to choose a set
point lower than the camera can cool (i.e., –50 degrees C) and read the actual temperature it is
able to achieve then adjust the setpoint to a few degrees above this minimum temperature.
This will work well if the ambient temperature does not rise during the night. If you notice that
the cooler must work at 100% power to attempt to maintain the setpoint, then you should raise
the setpoint approximately 3 degrees higher than the temperature the camera is actually able to
maintain.
3.4.

Focusing the CCD Camera

Before using the software to focus the camera the first time you should place a diffuser (such as
scotch tape or ground glass) at the approximate location of the CCD's sensitive surface behind
the 2" eyepiece holder and focus the telescope on the moon, a bright planet or a distant street
of the brightest object in the field of view. Point the telescope at a bright star. Center the star
image in the CCD, and adjust the focus until the star image is a small as can be discerned.
Next, move the telescope to a field of fainter stars that are dimmer so the CCD is not saturated.
Further adjust the focus to maximize the displayed star brightness in counts and minimize the
Section 3 - At the Telescope with a CCD Camera
Page 36
lamp. This preliminary step will
save you much time in initially
finding focus. The approximate
distance behind the 2" eyepiece
tube for the Research Cameras is
described in the drawing at right.
To achieve fine focus,
insert the CCD head into the
eyepiece tube, taking care to seat
it, and then enter the CCDOPS
FOCUS mode. The Focus
command automatically displays
successive images on the screen as
well as the peak brightness value