The Lake County Astronomical Society

The Cave Optical Company

Jack Kramer

If you've been into astronomy for more than twenty years, you've probably heard of Cave Optics, which at one time was a pre-eminent maker of mirrors and Newtonian telescopes for the amateur and government market. They had a solid reputation for the quality of their optics, and to this day a Cave mirror is eagerly sought after. The driving force was Thomas R. Cave, an inveterate Mars observer who went on to found the company that bore his name. In 1958 I built my first homemade reflector using a 6-inch, f/10 Cave mirror that was a superb performer.

Although he lived most of his life in the Los Angeles area, Tom Cave's interest in astronomy began in 1930 when he was eight years old and visited Chicago's Adler Planetarium. Shortly thereafter, he became particularly enthralled with the planet Mars.

As was the case with Clyde Tombaugh, Cave's observations as an amateur brought him to the attention of Lowell Observatory. He had sent reports of his observations of Mars with a 6-inch Newtonian to E. C. Slipher of Lowell. In 1941, Slipher offered him a position as observing assistant, but Cave was then working as an apprentice at an optical company and turned down the offer. He went on to become one of the most skilled opticians, and with help from his father, he founded his own company in December 1950.

Cave favored large instruments, and to some extent is responsible for making amateur astronomers realize that they could move beyond the usual 6-inch reflector that was common at the time. In 1949, Cave had produced a telescope for his own use - a 121/2-inch, f/11.3 giant. A friend of Cave's, O. R. Norton, was invited over to see it and is quoted in the August 1994 issue of S&T: "I arrived at 265 Roswell Av and passed through the gate to the backyard - and into another world. Before me stood a leviathan of a telescope, so large that it would have taken a 12-foot ladder to reach the eyepiece."

In 1956 and again in 1971, Tom was invited by Robert Richardson to observe the red planet at Mt. Wilson using the 60-inch and 100-inch telescopes at the Coudé focus. On August 10, 1956, they had perfect seeing for longer than 30 minutes on the 100-inch and observed visually with 1000X, 2500X, and even 3000X. The view was so good that Cave and Richardson forgot to take pictures. Tom writes: "The planet had extremely fine details and we felt that we were flying over the planet. The view was the most amazing one of Mars perhaps anyone has ever had from land-based stations. The steady view was totally beyond human description. There were no canals, just only exceeding fine broken details ... Mts of Mitchell detached from the south polar cap. At no other time have I seen more than 10% or 15% that we saw that night."

Large Newtonian telescopes up until roughly the late 1970's were heavy and ungainly pieces that often required a permanent installation of some sort. But the advertising tried to downplay their size. For example, an ad for the Cave "transportable" 121/2-inch shows a young woman standing next to it. The eyepiece was quite a bit over her head, but most people would assume that women tend to be shorter anyway. However, the female model chosen for those ads was 6-feet tall!

By the time Thomas Cave sold the business in 1979, Cave Optical had produced about 83,000 mirrors and 16,000 complete telescopes with mountings sold under the Astrola brand name. In the company's later years, they also made a few refractors. Cave had decided to sell the business due to ill health, but the advent of the newer Schmidt-Cassegrain design by Celestron created serious competition for his company, which had concentrated almost entirely on making telescopes of the Newtonian configuration on hefty German equatorial mounts. Cave Optical was soon liquidated by the new owners. Tom Cave himself continued to work part time in the optics business for other companies but retired for good in 1988. He passed away on June 4, 2003.

The Hardin Optical Company purchased the rights to the Astrola name and now sells telescope products under that brand. It's appropriate though - Larry Hardin got his feet wet in optics working for Tom Cave!