Orion PARSEC 8300M - Manual (Page 8)

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arrow button next to the preset name to
manage your presets, including Update
Current Preset, and Save As New
Preset. See MaxIm DL’s
Help Topics
for more detailed information.
readout Mode
In the
Expose Tab , select Normal for
the best image quality, and Fast for a
quicker image download.
Frame type
Choose,
Light (Raw or Color for the
8300C), Bias , Dark, and Flat. Please
read section 5, “Astronomical Imaging”
to determine when and why to take a
dark or flat.
Fan Speed
Select
Camera Settings in the Expose tab (Figure 14.1) to access the fan speed,
High, Medium, or Low (Figure 14.2). High is recommended for the best cooling
performance.
There are a large slew of settings in the
Camera Control Window’s Expose tab.
Please read MaxIm DL’s Help Topics which covers all the settings in greater detail.
3.2. the Screen Stretch Window
The function of the Screen Stretch Window (Figure 13) is to properly map the
image brightness levels captured by the camera into corresponding image bright-
ness levels on the computer screen. A typical camera image has each pixel (light
detecting site, over eight million pixels form a single Parsec image) represented
as a number (from 1 to 65535) depending on brightness. This has to be mapped
into the video monitor’s brightness range (from 1 to 255). It is important to set the
screen stretch appropriately, or a great image may look terrible!
When an image is displayed, you will notice a graph in the
Screen Stretch
Window. This is called the “histogram” of the currently displayed image. A histo-
gram is a simple bar graph that shows the range of brightness in an image. Each
bar in the graph represents a level of brightness; the bar to the far left in the histo-
gram represents the dimmest pixels, and the bar to the far right is for the brightest
pixels. The height of the bar is the total number of pixels at that brightness level
in the image. Every image has a different histogram depending on how much of
the image is bright or dark. Directly viewing the histogram of your image in the
Screen Stretch Window provides an easy interface for making decisions on how
the screen stretch should be set.
In Maxim DL, the two parameters entered in the
Screen Stretch Window are
Minimum and Maximum. A pixel that is at the Minimum value is set to zero (black),
and a pixel at the
Maximum value is set to 255 (white). An easy way to adjust the
Maximum and Minimum values is to
move the slider arrows located directly
under the histogram of the image in the
Screen Stretch Window. The red slider
arrow corresponds to the
Minimum
value and the green arrow corresponds
to the
Maximum value. Simply left-click
and then drag each arrow to adjust it
to the desired level. The best results
are obtained by adjusting the arrows
(numbers) until the most pleasing dis-
play appears.
There are also seven automatic settings in the
Screen Stretch Window. Typically,
Medium will give good results for deep sky objects, so the default screen stretch
setting is
Medium.
Instead of using the Screen Stretch Window, it is faster to use the Quick Stretch
facility. This allows you to modify the image appearance instantly with small up/
down and left/right movements of the mouse. To do this, hold down the Shift key,
then left-click and drag the mouse on the image. You’ll find this feature to be a
great convenience when fine adjusting the screen stretch to get an image to look
its best.
The trick with stretching is determining exactly how to stretch the image for best
effect. Often there are several different possibilities for the same image. Trial-and-
error will be the best way to judge what the best screen stretch setting is. Try
Figure 14.1. The Camera Settings is found in the Expose tab.
Figure 14.2. Adjust the Fan Speed in
the Parsec Settings.
Figure 13. The Screen Stretch
Window is a histogram that allows you to
adjust the apparent brightness levels of an
image on your screen.
Number of pix
els at
br
ightness le
vel
Range of brightness levels