CCD Imaging - What Was I Thinking? Part 2

Welcome to Part 2 of my multipart series on my experiences in learning the fine are of digital astrophotography. If you remember, in Part 1 I discussed all the equipment one would need to undertake this endeavor. As it happens, I already own a modest but rather well made Takahashi FC100 refractor, on an EM-10 equatorial mount. This telescope has a 4-inch objective lens and a focal length of 800mm, making it an f/8 optical system. A tad slower than I would prefer (I would rather have an f/6.3), but one makes do with what one has. The equatorial mount, being of 1980’s vintage, has motors on both axes for fine control, but no computer “GoTo” capabilities. All I needed was a CCD camera.

The camera I did purchase was the Orion Star Shoot™ Deep Space Color Imaging Camera. The small but totally adequate manual that comes with the camera suggests that you familiarize yourself with the camera and the controls in daylight.

This is a Good Idea.

Sadly, not one I heeded.

You see, I felt that my long-ago experience with wet film astrophotography coupled with my 30 years of experience in the computer software industry, I had no reason to spend any time reading the manual.

So, on a clear and crisp 30 degree evening about 25 miles from home out in the middle of nowhere I dutifully set up my scope, and spent about 45 minutes getting the EM-10 equatorial mount properly polar-aligned. I then proceeded to target the open star cluster M-45 (also known as the Pleiades, or Seven Sisters). I boot up my computer, attach the camera to the telescope, then, and only then, find out that the power cord for the camera does not have a standard DC jack at the end, but rather a “cigarette lighter” jack. The cord is 4 feet long and my truck, with the cigarette lighter, is 20 feet away. In fact, even if my truck were right next to the telescope, the cord would still not stretch. At this point it became clear to me WHY the sales person at Orion wanted me to buy the Dynamo Pro 12v DC Mobile Power Station ($99).

If I had only spent the five or so minutes it would have taken to read the little manual before venturing out I could have saved myself a lot of grief. Another trip to Orion Telescopes, and I am now the proud owner of the Dynamo Pro 17 12v DC Power Station. This baby also has 250 cold cranking amps of power to jumpstart a dead car battery, plus an 800,000 candlepower halogen spotlight (which I am sure my fellow astrophotographers will love).

Shortly after purchasing my Dynamo Pro 17 12v DC Power Station, I found out that Costco sells a unit that is fairly similar for only $49. Costco’s Power Station has 450 cold cranking amps and it has an air compressor for keeping your tires at their proper inflation as well as the ability to jumpstart your dead car battery. But it didn’t have the 800,000 candlepower halogen floodlight (only a 250,000 candlepower “work light”).

Having learned my lesson, I went back to the Orion StarShoot™ Deep Space Imaging Camera manual, and went through the process, step by step, in daylight, to learn the basic mechanics of camera operation. During this process, I learned how to properly focus the camera. Focusing with an eyepiece is simple – you look through the eyepiece and turn the focusing knob until the image is sharp and clear. The camera itself does not have an eyepiece.

Focusing the camera is a tedious process. First you must find an object in the telescope using an eyepiece, then bring it into focus. Next you remove the eyepiece and attach the camera to the telescope. Then you begin to take a series of images using what the manual calls "Focus Mode". In focus mode, the camera takes an image, downloads it to the computer, takes another image, downloads it to the computer, etc. The theory being: if the image is out of focus, you turn the focus knob on the scope a bit, and a successive image will note the change - either better focus or worse. You repeat this process until your image being downloaded is in "focus".

In the daylight you can practice by using the telescope to photograph a distant object. After several dozen iterations of taking an image and adjusting the focus knob, you do get an image that is in decent focus. For my test, I took a picture of a house under construction up on the hill about a half mile away. I also learned the difference between USB 1.0 and USB 2.0. My laptop, as it turns out, is 20th century technology, and only has a USB 1.0 port. It takes several seconds to a minute to download one frame from the camera to the computer. I thought this was Normal. Then I purchased a USB 2.0 PCI card, and wow! It downloads frames now in a split second! (I inserted this little lesson here, though I really didn’t learn it until about the 4th time out in the field… I thought someone might benefit from knowing this now rather than later…)

The next step: photographing an easy target - the Moon! My first opportunity to photograph the Moon is coming up shortly (note these events occurred two years ago; I am only now putting my notes down in narrative form). Wish me good weather! And stay tuned for my experiences with that endeavor! Oh - and for those who think, based on my description so far that polar alignment and focusing are easy, we shall address each of those activities in detail in a future post.