Home Page    Directory    Specials    My Account    My Wishlist    My Basket  

This section takes you through the most basic procedures for taking CCD images with CCDOPS.  The only techniques employed are taking single exposures and taking dark frames.  Using only these techniques you can take very impressive CCD images of many objects.  More advanced techniques are covered in the following section.

Grab

Once you have focused the telescope and found your target, the easiest way to capture an image is using the Grab function.  Click the Grab button on the toolbar or select Camera > Grab from the main menu.

Above:  The CCDOPS Toolbar.

In the Grab window, select an exposure time.  The exposure will be limited by the accuracy of the telescope's drive motor and the focal length of the telescope.  The longer the focal length, the shorter the exposure will need to be to keep the stars in the image from trailing.  30 to 60 seconds is a reasonable starting point for most telescopes.

Note:  Self-guided CCDs can take much longer exposures, but the techniques involved are more advanced so they are covered in the Advanced Imaging section.

Tip:  When first using your CCD system, try taking longer and longer exposures until you see trailed star images, then use the longest exposure time without trails.  For example, if 60 seconds produces trailed stars but 45 seconds leaves the stars sharp, use 45-second shots.  Later you will be able to stack multiple exposures to achieve the effect of a single longer shot.

Select Also from the Dark Frame pull-down menu, make sure image size is set to Full and Special Processing is None.  Click OK to take the image.

CCDOPS begins by closing the shutter and taking a dark frame which will be subtracted from the light exposure to remove noise.  Later you may wish to do this manually, but for now using the Auto feature is most convenient.  You will see an status bar indicating the progress of the exposure.

Once the image is completed it will be downloaded (Auto dark frames are not displayed).

Download time will depend of the camera and the connection type being used (parallel, USB, etc.) but typically will be 15 seconds or less.  Next, the Clear filter is selected and the light exposure is taken with the shutter open.

Once downloaded, the final exposure (automatically dark-subtracted) is displayed.  Simple enough!

Note:  You can use the Grab technique to take as many individual images as you like, but you will need to use another program such as MaxIm DL to combine them. 

 

Color Grab

The simplest way to take a color image with CCDOPS is using the Color Grab function.  Select Grab from the toolbar or Camera > Grab from the main menu.  Set the Grab window parameters as above but change Special Processing to Color Grab.

When you click OK the Color Grab Setup window appears.  This allows you to set the file names and directory for the three images which will be taken.  The images are saved as separate files and then combined later to form a color image.

Begin by clicking on Set Name/Dir and choose a name for the files (one name suffices as each file is appended with either an R, G, or B to indicate which filter was used to take the image).  Leave file type as Compressed.  Set the desired exposure time in the Red exposure field.  If you wish for the Green or Blue exposures to be different you may change the multipliers to alter the exposure times (for example, a 60-second red with a 1.5 Blue multiplier results in a 90-second blue exposure).  Most often the multipliers are left set at 1.  Click OK to begin taking the images.

Tip:  Make sure Reuse dark frames is set to Yes in the camera setup (Camera > Setup or Setup on the toolbar).  This means only one dark frame is taken for exposures of the same length (eliminating two exposure from the Color Grab sequence).

A dark frame is taken first.  Then the Red filter is selected, an exposure is taken and then displayed on screen.  Next, the green and blue exposures are taken, and as each one is displayed the previous image disappears.  Each image has automatically been saved.

Be sure to visit the Image Processing with CCDOPS section to see how to combine these images to create a color picture.

 

Next, Advanced Imaging....

Next Page



Copyright ©2000-2014 Starizona
Adventures In Astronomy & Nature, All rights reserved
5757 N. Oracle Rd., Suite 103 · Tucson, Arizona 85704 · Call Us: (520) 292-5010
Map & Directions -  Return Policy