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To properly position the parfocal ring on the eyepiece barrel, first insert the
camera into the telescope’s focuser drawtube. Set MaxIm DL Essentials so
the camera displays on the computer’s screen in
Live Video
mode. Focus
the camera as precisely as possible by visual inspection of the image on your
computer screen. You do not need to actually capture an image, just look at
the live preview on the computer. If you have a focus lock thumbscrew on
your telescope’s focuser, tighten it firmly once sharp camera focus is achieved
(Figure 8a). Place the parfocal ring on the eyepiece barrel, and slide it up the
barrel as far as it will go and loosely tighten the thumbscrew on the ring (Figure
8b). Now, replace the camera with the eyepiece, being careful not to change
the position of the focuser drawtube. Bring the eyepiece into focus by sliding
it in and out of the focuser drawtube (Figure 8c). Do not use the focus knob of
your telescope to focus at this time.
Note: If you cannot obtain a focus with the eyepiece by pulling it out of the
focuser drawtube, you will need to try another eyepiece.
When the eyepiece is in focus, tighten the securing thumbscrew on the focuser
drawtube to secure the eyepiece in that position. A significant portion of the
eyepiece’s barrel should be extending out from the focuser drawtube. Now,
slide the parfocal ring down the eyepiece barrel, and seat it against the focuser
drawtube (Figure 8d). Securely tighten the thumbscrew on the ring. The parfo-
cal ring is now properly positioned on the eyepiece’s barrel.
Now that the parfocal ring is properly positioned, focus the camera by first
focusing with the eyepiece. Simply insert the eyepiece as far as it will go
into the focuser drawtube, and focus with the telescope’s focusing knob.
Then, replace the eyepiece with the camera, and the images on the computer
screen should be very close to focused. Use the live preview mode to achieve
a precise focus with the camera. You’ll find that using the parfocal ring on an
eyepiece will serve to focus the camera much more quickly.
astronomical Imaging
Now that you’re familiar with basic camera and software operation, it’s time to
take the SSSSI-III 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 of multiple
exposures as planetary images do.
Imaging the Moon
Imaging the Moon is much like imaging terrestrial objects during the day. Since
the exposure is very short, it is not critical that the telescope be precisely polar
aligned. Best focusing will be achieved by first focusing on a bright star near
the Moon.
When the moon is past half full, it is hard to get detail due to the tremendous
glare off of the lunar surface. Most detail, even on a sliver of a moon, will be
at the terminator (that tiny thin line between the shadow and light, see Figure
9). To get more of the moon in the image, a focal reducer will need to be used.
For close-ups of craters use a barlow lens (see “Using Focal Reducers and
Barlow Lenses”).
Imaging Planets
The best planetary images will be obtained by stacking (combining) many indi-
vidual images in order to improve image contrast, brightness, and detail.
Since you will be taking multiple images over a period of time, it is important
you have a decent polar alignment in order to keep the planet within the field of
view of the camera. To this end, having a motor drive (at least single-axis) will
also be helpful. Otherwise, you will periodically need to rotate the R.A. slow-
motion knob to keep the planet within the camera’s field.
To take multiple images of a planet for stacking:
1. Acquire the planet into the field of view of your eyepiece that has the parfo-
cal ring attached to it, and center it in the eyepiece’s field of view. Focus
the eyepiece with the telescope’s focuser. If you are using an equatorial
mount with a motor drive, make sure the motor drive is on and engaged.
2. Remove the eyepiece and replace it with the SSSSI-III. If the parfocal
ring was set properly on the eyepiece, the camera should be close to
focused.
3. Focus the camera using the telescope’s focus knob. If you are having trou-
ble determining best focus, try focusing on a bright star near the planet.
You can also use the histogram functions for most accurate focus, this will
be explained later.
4. In the
Camera Control Window
, set the Mode to Light Color 1x1.
5. Set
Frames
to somewhere between 1 and 10 to start. This number indi-
cates the number of frames MaxIm DL Essentials will actually put into
each individual captured image. Be careful not to set this number too high,
especially if seeing conditions are poor. Otherwise, the captured images
will be blurry.
Figure 9.
The Moon’s surface detail looks
the best along the terminator.
