Orion 52080 User Manual
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Important Note: Dark frames (Dark Raw 1x1) should only be subtracted from
Light Raw 1x1 images. If you try to subtract dark frames from images that are
already color-converted (i.e. Light Color 1x1 images) the resultant image color
will be incorrect .
To take dark frames for subtraction from “light” images:
1. In the Camera Control Window, set the Mode to Dark Raw 1x1.
2. Set the exposure time to whatever you set it to (or will set it to) for taking
actual (“light”) images.
Note: When taking dark frames, do not change any of the settings in the
Setup
button from what they were (or will be) when “light” images are taken.
3. In the box beneath the Mode box, choose Autosave. Now set the number of
dark frames you would like the camera to take under Autosave (3 to 10 will
generally suffice, as these will be averaged together), select the file folder
in which you would like to save the dark frames with Folder, and enter in a
Base filename for the captured dark frames. Typically the name of the object
being imaged with the word “dark” added, such as “OrionNebula1dark”,
will be entered here. If “OrionNebula1dark” is the Base filename, and
you choose to Autosave five images, then the images will appear in the
selected file folder as “OrionNebula1dark_0001.fit”, “OrionNebula1dark_
0002.fit”, “OrionNebula1dark_0003.fit”, “OrionNebula1dark_0004.fit”, and
“OrionNebula1dark_0005.fit”. Using the word “dark” in the Base filename
will help you distinguish between light and dark frames when combining
later.
4. Click Expose, and Maxim DL Essentials will indicate the camera needs to
be covered to take a dark frame. Cover the front of the lens you are imaging
through, and then click OK. The camera will commence taking and saving
the dark frames.
Now that you have acquired several dark frames, combine them into a single
averaged dark frame for subtraction from “light” images:
5. In the Process menu, select Setup Dark Subtract.
6. In the window that pops-up, click Remove All if any filenames appear in
the window.
7. Click Add, and select the file folder location for the dark frames taken.
Select the dark frames and click Open.
8. The selected dark frames will now appear in the pop-up window. Click OK.
The dark frames have now been averaged and stored into memory.
You are now ready to subtract the averaged dark frame from “light” images.
This should be done to individual light images BEFORE combining them
together. There are two ways to do this. If you take dark frames first, before
taking light images (using Light Raw 1x1), then you can automatically subtract
the averaged dark frame from each individual light image as it is captured. If
you take dark frames after you have already taken the light images (using Light
Raw 1x1), then you can subtract the averaged dark frame from each individual
image before you combine them into a single, final resultant image.
To automatically subtract the averaged dark frame from “light” images as they
are captured:
1. Setup the averaged dark frame as outlined previously.
2. Acquire the deep sky object into the field of view of your eyepiece, and cen-
ter it in the eyepiece’s field of view. Focus the eyepiece with the telescope’s
focuser. Make sure your equatorial mount’s motor drive is on and engaged.
Remove the eyepiece and replace it with the SSDSI-II. If the parfocal ring
was set properly on the eyepiece, the camera should be close to focused.
Precisely focus the camera by using the telescope’s focus knob and the
Fast Focus (or Focus) setting in the Camera Control Window.
3. In the Camera Control Window, click the Dark Subtract square so it is
checked. Once this box is checked, every subsequent light frame taken
with the camera will have the averaged dark frame automatically sub-
tracted.
4. Now, set the Mode to Light Raw 1x1. In the box under the Mode box, select
AutoSave. Set the number of images you would like the camera to take
under Autosave (start with 5 or so), select the file folder in which you would
like to save the images with Folder, and enter in a Base filename for the
captured images. Set the exposure time equal to that of the dark frames
taken prior.
5. Click Expose, and the camera will commence taking the images. When it
saves each image file to its designated Folder location, it will automatically
subtract the averaged dark frame.
6. Before these images are ready for stacking, they must be converted from
raw format to color format. To do this, open all images to be stacked in
Maxim DL Essentials. Click on one of the images and select Covert Raw
to Color from the Process menu. For convenience, there is a button on the
toolbar that you can click instead of using the menu. Now, click the Reset
Background Level and the Reset Scaling button (scaling can be used to
fine-tune the color balance later on). Make sure the Anti-Alias Filter box is
not selected. Click OK. Repeat this for all the open images.
These images have the averaged dark frame subtracted and have been color
converted. These are now ready for stacking (using the Combine function).
You can Save the individual images, or just save the combined image after
stacking.
If you have already taken your “light” images (remember that these must be
Light Raw 1x1 NOT Light Color 1x1), then you will need to manually subtract
the averaged dark frame from each image prior to stacking them into one
combined image. To do this: