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4.1. Focusing
Focusing the CCD camera is one of the most critical parts of imaging. It can be
challenging, but MaxIm DL has some helpful features which will assist you when
focusing your Parsec. Before focusing, make sure your mount is polar aligned and
tracking.
For best results, we recommend focusing on a star at least 30° above the horizon
(or higher). Follow these steps to achieve an accurate focus:
1. Find and center a moderately bright star through your finder scope. Try to
find a star around magnitude 4 or 5. If you are not using an optical finder
or just using your unaided eye, the star should look relatively faint. This is
important because brighter stars will easily over saturate the camera and
compromise the focus accuracy.
2. Center your telescope on the star using an eyepiece. Make sure the right
ascension (R.A.) tracking motor is engaged on your mount.
3. Replace the eyepiece with the Parsec.
4. Set the
Exposure Preset to in the Camera Control Window’s Expose tab
to
Focus.
5. Click the
Expose button. You should see the out of focus star in the image. If
you do not see anything, you need to increase the exposure time.
6. Check that the
Subframe section has both the On and Mouse boxes
checked on.
7. Draw a small box around the unfocused star with your mouse (hold-click and
drag the mouse cursor around the star to draw the box, Figure 15).
8. In the
Expose tab, towards the right, select Continuous. Click Expose
.
The
camera will only download the area you previously selected, which makes
each image download significantly faster than the whole frame.
Note: If the Parsec is grossly out of focus, no object will appear in the image, not
even a blur. Increase the exposure time if needed and patiently move through the
focus range of your telescope until you see the centered star come into view.
1. Gradually adjust the telescope’s focuser inward until the star visually comes
to a small point on your computer screen. You have achieved a rough focus.
Some small adjustments remain to get a perfect focus.
2. Click the
Stop button.
3. Set
Seconds somewhere between 0.1 and 3 seconds (or longer for fainter
stars), depending on the brightness of your star.
several different settings until you find one you think looks best. When the image
is subsequently saved, the screen stretch setting information will be kept when
the image is next opened. Feel free to adjust the
Screen Stretch settings all you
want; it will not effect the image data you captured and only effects how the image
is displayed. You can always switch back to a preset setting, like
Medium or Moon.
4. Astronomical Imaging
Now that you’re familiar with basic camera and software operation, it’s time to take
the Parsec out at night under the stars to capture some astronomical images. We
recommend starting with the Moon, as it is easy to acquire into the camera’s field
of view, and typically does not require stacking multiple exposures like planetary
and deep sky images do.
Figure 15.
Subframe around the star you want to focus on by drawing a box around it
with your mouse.
