The above image is the Menu and Buttons of the application. From left to right, the buttons are:
Save: Saves the current image
Autosave: Autosaves all captured images, as per the data on the Exposure window
Display: Toggles display window on/off
Sub-frame: Selects a specific area of the image instead of the full frame. Very useful for focus
-
ing.
Full frame: Selects the full area of the CCD
Exposure: Toggles the exposure window on/off
Expose: Initiates the exposure of the duration selected in the exposure window
Loop: Toggles the loop exposure on/off. Usefull for focusing and capturing sequences
Another interesting feature is the “Quick” menu. By pressing F1-F8, you will
start immediately an exposure of the predetermined duration, either in full reso-
lution or in binning 2x2.
The first image
To start, center your telescope visually on a moderately bright star. Put the camera on the telescope’s
focuser and press the F1 key. This will immediately initiate an 0.1s exposure. When complete, you
should see a strongly defocused star in your computer screen. Congratulations! Everything is work-
ing as expected. If the star is grossly saturated (completely white circle), then you should manually
select a smaller exposure on the Exposure window.
Focusing
Depending on how defocused is your star, click on the Sub-frame button, and select an area around
the star. This will limit the data size being downloaded to the computer, making it much faster.
Click on the Loop button and then on the Expose button. This will start an exposure that wil repeat
itself until the Loop button is pressed again. Focus your telescope until the star looks like a star,
and not a large circle.
Artemis Capture offers a simple tool to help you acheive precise focus. Un-
der the “View” menu, there is a Focus Assist option. Basically, it measures
the star brightness and width, displaying the values. Best focus should be
achieved when you have the smallest star width and the highest brightness
level. To use this feature, simply double click on a nearly focused star.
Centering and final exposure
Assuming that your target object is already in the field of view of the CCD, you should now do a
longer exposure to aid you in centering. It will depend on your telescope configuration, but 5 sec
-
onds should be enough to record the position of most bright deepsky objects.
After centering, is time for the final exposure. It’s duration will also depend on many things, but
you’ll want to do the longuest exposure that your system can do, depending of course of the object
being imaged. For example, a 5 minute exposure on the Andromeda galaxy will burn out the core
for sure, but it will nicely record the outer arms. You can do 2 exposures of different lenghts, and
then combine them on a processing software, but thats another story... ;-)
