In the last decade, automation of telescopes and digital photography significantly changed the quality of the amateur experience. The modern GoTo computerized drive systems reduced the alignment process to a few minutes or less, in addition to tens of thousands of cataloged celestial objects to navigate to in seconds. Using digital photography and modern processing software, amateur astronomers see the results of their labor appear overnight. In times past, film canisters were dropped of with the local photo lab and results appeared days or a week later.
The innovation doesn't stop here. With interfaces to the computerized telescope mounts, sophisticated software reads imagery from webcams attached to guide scopes or off-axis prisms and sends digital messages to the drive systems to keep the telescope tracking an object with long-term precision. An automated process and equipment setup commonly known as auto-guiding.
Defects and manufacturing variances inherent in worm gears produce regular tracking error imperceptible to the visual observer. However, the precision sensors in digital cameras detect and store tracking errors in seconds. Subsequently, the common understanding in the amateur community maintains that auto-guiding is essential to high accuracy astrophotography.
So, there you have it. Just as has been done for decades past, opening the shutter to a 35mm SLR camera for an hour or more, so too can the modern astronomer open the shutter to his digital SLR or CCD camera for an hour or more...with a lot of computer-aided assistance and setup, of course.
So, why on Earth would you not auto-guide?
Well, the additional time, cost, and complexity for starters. Secondly, the assertion that auto-guiding is "essential." This element of modern astrophotography highlights the central concern that lead to my pursuit of the unguided technique.
Amazingly, using only a programmable calculator as an intervalometer, an amateur astronomer can master unguided astrophotography at a fraction of the cost and learn more about data fusion in the process.
More on this unguided technique, later.