Telescope Technology and Amateur Astronomy
Jack Kramer
Prior to the 1960's, most amateur astronomers ground their own mirrors and built a Newtonian (reflecting) telescope or else they spent top dollar for a commercially-made refractor or Newtonian. Commercially-made optics were not widely available at reasonable prices. The cost-conscious person had to learn the basic principles of optics, then dive into the task of grinding and polishing a mirror. But gradually the cost of high-quality completed mirrors began to come down as mass-production techniques took over. The most tedious aspect of grinding a mirror is the initial generation of the curve in the glass to the desired focal ratio. Motorized grinding machines have taken over this job among manufacturers. If you weigh all the costs today, you'll find that it's still cheaper to grind your own mirror...but not by much. If you take into account the time and effort required, then it makes very good sense to purchase a completed set of mirrors. Then beginning in about the mid-1980's, mass production made good quality commercial telescopes available to amateur astronomers as complete relatively low-cost packages. There are still many amateurs who take pride in their skill as telescope makers, and there are few thrills comparable to exploring the universe with a telescope you yourself have made. But several commercially made instruments have achieved such a high level of sophistication, quality, and economy that many people opt to purchase completed telescopes. A good telescope is a lifetime investment; if properly maintained, it will never wear out. Witness the fact that some telescopes built a hundred years ago are still in daily use.
The issue of quality is always important, especially when considering the telescopes that are sold in department stores. As a general rule, these telescopes are seriously deficient in some aspect. Despite outward appearances, the mountings are often unstable and the optical components are usually of poor design and quality. The only usable department store telescope is the top-of-the-line model priced in the range of $250-$300. Anything that retails for below $100 is absolutely worthless for astronomical purposes! But the most serious problem is that department store telescopes are advertised as providing magnifications much higher than they are capable of giving. Don't believe claims of 450x or more from a 60mm refractor! The purchaser takes the prize home only to discover that it's virtually impossible to see anything with it. It's no wonder that many people lose their enthusiasm for astronomy when faced with the insurmountable problems of using an inferior telescope. Light gathering is far more important than the ability to magnify the image. Almost as important is having a solid mounting, because if the telescope can't be aimed with ease and held steadily, you simply won't be able to see anything in the sky. Bear in mind that there is a difference between telescopes intended strictly for terrestrial viewing and those for astronomical purposes. In astronomy most objects are extremely small and dim, pointing upward toward the sky is awkward, and the night is dark with few landmarks for the novice observer. All these factors underscore that being an amateur astronomer is not always easy, so you don't want your telescope to be a further impediment. Sometimes, the best way to get started in astronomy is simply to purchase a good pair of binoculars or low-power spotting scope.
