Hardware: Cameras

Figure 1 - Chip size comparison
of the DSI Family

The DSI III cameras represent the top of Meade’s line of cameras and the latest in the evolving DSI series. The original DSI sported a 6 mm (diagonal) chip and 510x492 resolution and the DSI II that followed stepped up to an 8 mm (diagonal) chip and 748 x 577 resolution. The new DSI III cameras stet up to an 11 mm (diagonal) chip and enter the megapixel arena with 1360 x 1024 pixels. Here, we see the relative physical sizes of the three sensors. All of the cameras use Sony HAD CCDs, with the DSI II sensors (Sony ICX 429 series) and DSI III sensors (ICX 285 series) finding their way into numerous other cameras on the market. At time of this writing, the DSI III cost $1299 (color and monochrome without filters), while the DSI II cost $599.

Capturing images from the sky is a complex process. Starlight passes through the atmosphere, through your telescope, through the filters in your camera, until it finally strikes your camera’s image sensor. In the controlled environment of the camera body, photoelectrons accumulate on a CCD image sensor, your camera’s electronics read out the CCD, digitize the signal, and pass data to the driver software in your computer, until it finally reaches the image acquisition software.

I wrote this story for savvy amateur astronomers who are looking for a top-notch CCD camera that is suitable for both imaging and science purposes, especially if you want a high-quality camera that seems to help you make great images. Since I’ve been involved with CCD cameras for quite some time, I’m amazed at the number of fine imaging cameras available to amateurs on the market today. But this story is about just one: Quantum Scientific Imaging’s 532ws CCD camera.

So you just got a brand new Orion StarShoot™ Deep-Space CCD Color Imaging Camera and you are looking to capture your first image but are not sure where to start? This is the article for you. For the sake of brevity, we will refer to the camera as the StarShoot and acknowledge the fact that the name is a trademark of Orion Telescopes and Binoculars. The intent of this article is not to make you a master astro-imager but to help you get started along that path.

First off, astrophotography is not easy, but it can and will be very rewarding with a little patience and some practice. If your first images do not look like something off of the Hubble web site, don’t get discouraged – you can and will get better with some patience, practice and a little diligence.

As the author of PHD Guiding, I am often asked by users for my opinion on various guide camera solutions. My advice is typically to favor cameras that are a) capable of exposures of several seconds, b) monochrome, and c) have a reasonable sized chip. Unfortunately, webcams, the cameras may want to use for guiding don't fit the bill. Most are limited to about 30 ms exposures and almost all use small color chips. The short exposures and presence of color filters over each pixel conspire to limit the choice of guide stars to bright stars (e.g., mag 4-5). Given the small swath of sky covered by a small chip, makes finding a suitable guide star even more challenging. When standing out in either a freezing cold or hot and mosquito-infested field, the last thing I want to be doing is hunting around for a suitable guide star.

If there has ever been a true revolution in astrophotography, it has been the rise of Digital Single Lens Reflex cameras (DSLR’s) as a viable alternative to film and expensive CCD cameras. Chemical emulsion based photography has pretty much died a slow death over the past decade with good astronomical films becoming rare. Specialized CCD cameras with their cooled sensors are optimal for astro work, but are very expensive compared to DSLR’s and require a high level of technical expertise to operate successfully. Being designed and manufactured for a huge worldwide market, the powers of mass production have brought us astrophotographers an affordable single-shot color camera with every bit of the sensitivity and resolution of film but with the all-digital ready-to-process output of CCD’s.