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Resolution
High Res
Med/Low Res
Once the best focus is found, the focusing operation can be greatly
shortened the second time by removing the camera, being careful not to
touch the focus knob, and inserting a high power eyepiece. Slide it back and
forth to find the best visual focus (don't touch the focus knob), and then
scribe the outside of the eyepiece barrel. The next time the camera is used
the eyepiece should be first inserted into the tube to the scribe mark, and the
telescope visually focused and centered on the object. At f/6 the depth of
focus is only 0.005 inch, so focus is critical. An adapter may be necessary
to allow the eyepiece to be held at the proper focus position.
Finding and Centering the Object
If you have difficulty finding an object after obtaining good focus, check to
be sure that the head is seated at best focus, then remove the head and insert
a medium or low power eyepiece. Being careful not to adjust the focus
knob on the telescope, slide the eyepiece in or out until the image appears in
good focus. Then visually find and center the object, if it is visible to the
eye. If not, use your setting circles carefully. Then, re-insert the camera
and use the Focus Mode with an exposure time of about ten seconds, if the
object is quite dim. Center the object using the telescope hand controls.
Taking an Image
Take an image of the object by selecting the Grab command and setting the
exposure time. Start out with the Image size set to full. The camera will
expose the CCD for the correct time, and digitize and download the image.
One can also automatically take a dark frame immediately before the light
image using the Grab command by selecting the Dark Also option. This is
useful for really dim objects.
Saving Images
Save the images using the Save command in the File menu. We strongly
recommend you save images in SBIG Compressed or FITS format as they
are the most compatible. Use the TIFF and JPEG formats only when you
are done with the image as you won't be able to reopen it with CCDOps.
Those formats are useful for exporting to image processing programs.
Further Adventures
At this point we refer you to the CCDOps Manual that can be found on the
SBIG Software and Catalog CD-ROM. It has an extensive tutorial section
and detailed information about the software and its capabilities.
SBIG ST-i Manual
Saturation Counts
~65,000
~65,000
22
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