I’m a visual astronomer. I’ve tried astrophotography a few times, but have never been very happy with the results or willing to put in the time and money necessary to improve them. I’ve pretty much come to think of astrophotography as the rich man’s end of the hobby. But the appearance of relatively inexpensive (under $100) devices for acquiring images of solar system objects recently attracted my attention, and made me decide to give it another try.
The Orion® Starshoot™ camera was my first choice because it came with a stripped down version of the industry standard image acquisition and processing software MaxIm DL™. The camera itself is a small lightweight device that pops into the eyepiece holder of any telescope, though it requires a bit of in-travel compared to most eyepieces. The camera connects via the supplied cord to the USB port of your computer. Here I hit my first glitch. Though Orion says the camera will work with either USB1.1 or 2.0, the software requires USB2.0, which none of my computers had. I had to borrow another computer with USB2.0 to proceed; an alternative would be an add-on card to provide a USB2.0 port. With USB1.1 the image is extremely grainy and unusable.
Jupiter was the only suitable target during the period I borrowed the laptop. I mounted the camera on my Starmaster 11” Newtonian. At first I tried using the camera at prime focus (1200mm focal length), but found the image of Jupiter way too small. I added a TeleVue 2.5x Powermate, which gave me a larger image scale (3000mm focal length), but even this was barely enough. Unlike a normal camera, there are no controls on the StarShoot: it is entirely controlled by software, in this case MaxIm DL™ Essentials. My first night out, I experimented with various settings, but managed to grossly overexpose every image. The manuals provided by Orion are excellent although, in this case, I would have liked if the sections of the manual describing the operation of the software were clearer.
The second night, I had read the manual more carefully and managed proper exposures. The standard technique today for planetary imaging is to make a large number of individual exposures, and then later combine them (a process called “stacking”) in software. There are two ways of exposing image sequences with this camera. One is to take an automated rapid series of images, stored one at a time; the other to actually shoot a video, which is stored as a single file, but which can be broken out in the provided software into individual frames for stacking. I found the second method the easiest to use and work with. The trickiest part of image acquisition was getting the focus right. The software presents a series of live images from the camera, and you have to focus with a slight time delay between what you see and what you get. There is a method of computer assisted focusing, but I didn’t get into that.
One thing that rapidly became apparent is the need for lots of hard drive space. In each of my three sessions I spent about five minutes each acquiring images, and ended up with about 500 MB of data each night! The next day, I experimented with the MaxIm DL Essentials software, and learned how to stack images. I then transferred the images to my Macintosh, and did a bit of touching up with Preview, the simple graphics program provided free with every Mac. Here’s my result from night two, 2006 July 19 01:36UT:
As with most planetary images, south is at the top here. There are two white ovals clearly visible in the northern part of the Equatorial Zone (bright band close to equator) with several dark projections visible along the south edge of the North Equatorial Belt (dark belt just below equator).
The next night, the Great Red Spot was on Jupiter’s central meridian. I again shot a variety of exposures and then combined them into the following image, 2006 July 20 01:35UT:
The Red Spot Hollow is clearly visible in the southern edge of the South Equatorial Belt, along with a hint of the thin streak enclosing the Spot itself. The Spot shows no color in this image. Some other details visible in this image are the thin line of the Equatorial Band, a narrow belt which lies right on Jupiter’s equator, and a dark shading across the whole of the Equatorial Zone, which was readily visible at the eyepiece. The brownish red color of the belts also shows up well in this image.
While these results are far from the high resolution images widely published by experienced planetary imagers on the internet, they are very pleasing to me, as they show much more than I had any reason to expect in only a few sessions. With a larger image scale, more careful focusing, and more experience stacking and manipulating images, I feel I could vastly improve the quality of these images. The camera itself and the software that accompanies it are more than adequate for such a task.
Geoff has been a life-long telescope addict, and is active in many areas of visual observation; he is a moderator of the Yahoo "Talking Telescopes" group.