Image of the Month
Learning CCD Imaging
After taking my first image with the Starshoot CCD camera and the Orion 80mm APO refractor, I was amazed at how well it had turned out, even though I had used the wrong setting on the camera. Because I was not familiar with the Maxim DL Essentials software, I had inadvertently set the camera mode to "color", thinking this was the mode to use for a color image. Later, I learned that the camera mode should have been set to "raw". This setting allows you to stack, calibrate (by subtracting "dark" frames), and stretch the images (using the software Log Stretch function). Since my first image was taken in "color" mode, I could do none of the above functions, and could only use the histogram tool to stretch the overall image. This limited the amount of fainter stars I could bring out without "blowing out" the brighter portion of the image.
The next weekend, I tried again, this time with the globular cluster M-13 as my target. This time I was careful to set the camera mode to "raw" for the light images. I also took an equal number of "dark" frames to use in the calibration function. When processing these images, I found out that subtracting the "dark" frames greatly reduced the amount of electronic "noise" in the background of the image. Also, after the images were stacked, I used the "color convert" function to show the colors captured in the image. And, finally, I was able to use the "Log Stretch" function of the software to bring out the fainter outlying stars in the cluster. Comparing the first image of M-3 to my second image of M-13, below, shows the results of the first steps in my learning curve:
First CCD image taken on 5/26/2006. The twenty 30 second exposures were incorrectly taken in "color" mode. This allowed for no dark frame subtraction or log stretch function. Only "histogram stretch" could be used, limiting the outlying stars that could be brought out without "blowing out" the inner core of the cluster.
Second CCD image, taken a week later, with the camera set in the correct "raw" mode. The twenty 30 second exposures were calibrated with dark frame subtraction, then converted to color and stretched using the Log Stretch function in Maxim DL Essentials. Note many more outlying stars, but no "blown out" core.
Climbing the Learning Curve
A few months later, after learning more about image aquisition and processing, I took this exposure of M-27, the Dumbbell Nebula. This was the "deepest" image I had yet attempted:
thirty 60 second exposures stacked and integrated for a 30 minute integration. I was thrilled by the color seen in this image!
A month after the image to the left, I attempted an even "deeper" image. This is an integration of sixty
60 second exposures, stacked and combined for a one hour integration. This image was really exciting to me, not only for the beautiful color, but also the fact that I captured the "Pillars of Creation" feature of the Eagle Nebula, M-16.
Early in 2007, after 6 months of experimenting with different exposure lengths, learning more about the processing options in Maxim Essentials, and improving my ability to focus, I attempted to image my very first GALAXY: This is the barred spiral galaxy NGC-2903 in Leo. A 1 hour integration of 60 second exposures brought out the central bar and
some of the spiral structure! Now I was really hooked on CCD imaging.