Brashear is the name of the company that made our objective optics and was named for its founder. John Alfred Brashear only had a public school education. From school he became an apprentice to a machinist and at the age of 20 became a master of the trade. In 1861 he went to Pittsburgh and found employment. For the next 20 years he worked as a mechanic in a steel mill. In the meantime he broadened his elementary knowledge of astronomy and made amateur telescopes in his spare time. In 1870 Brashear built his first telescope in his South Side home and immediately opened his doors to neighbors, friends and strangers to observe the sky. Dr. Samuel Pierpont Langley, the director of the Allegheny Observatory, encouraged him to establish a workshop for astronomical instruments. The workshop became the John Brashear Co. and later the Contraves Corp., an internationally known maker of superb optics. He died in 1920 leaving a legacy of craftsmanship and astronomical instruments still treasured and used today.

This sketch was excerpted from a nice brief biography of Brashear at this site.

Mark Yingling, Precision Mechanical Assembler, inspects the +100-year-old glass from the disassembled objective. The bronze cell is in the foreground. The three tiny rectangular pieces above it are paper shims used to hold space between the two glass elements. Yingling carefully cleaned all of the glass surfaces and, later, reassembled the cell with the elements in the same relative positions as when he found them. He observed, however, that the elements appeared to fit best with the crown glass element forward. Yingling has also worked as a volunteer with the Wagman Observatory, Pittsburgh, which owns an 11-inch Brashear refractor.

There was one nasty surprise greeting technicians when the glass elements were removed from their cell. One of the 9-inch lenses, the flint, had two chips on its edge. Left alone, we were told, chips like those can lead to a spreading crack and fracture of the lens! Here Ron Grzybek, Glass Shaping Specialist, skillfully "stones," or polishes the chipped areas smooth in an effort to prevent cracking.

Here the cleaned, repaired, and reassembled objective is subjected to modern optical tests. We are viewing the cell (foreground) from the "inside" face ... that side facing down the telescope's tube assembly. Among the questions asked: will the lens perform best assembled, as was typical of Brashear objectives, "flint-forward" (flint glass facing the stars) or "crown-forward?" Metrologist Eileen Geary ran the tests.

The cleaned and reassembled objective was mounted on an optical table and Zygo interferometric testing performed. Flint-forward means the flint glass element of the two-part (doublet) objective was placed in the cell position facing the sky; the crown glass element was inside the telescope tube facing the observer. Flint-forward is rather unusual design but typical of many Brashear Co. objective lenses. Click the image to see it full-size.

"I raytraced a simulated BK-7 Crown and F2 Flint lens that was optimized for 486nm=blue , 587nm=green and 656nm=red light in the visible spectrum and indeed found that for Crown forward the blue and red have minimum OPD errors leaving the green OPD errors slightly higher. When light goes through the lens in reverse with Flint forward the attached curve flips leaving the green light minimized OPD. So the only conclusion I believe is that for yellow and green light stars the Brashear flint forward design may be more appealing to the human eye." -- Andrew Clarkson, Director of Engineering, Brashear L-3 Communications

After considering information and advice provided by antique telescope experts and the good folks at Brashear L-3, we traveled back to Pittsburgh and asked that the objective be reassembled with the crown element forward. Yingling (seen above) did the work and believed the elements were correctly interfaced with each other so, as discussed above, the glass assembly was essentially flipped inside the cell, and reassembled. The graphic to the left is the result of an analysis made after the objective was reassembled with its crown element forward. Looking at the results of modern optical testing, Brashear staff expressed their admiration of the precision work done by those who originally created the optical elements, by hand, more than a century earlier.

While the objective was apart, metrologist Geary took precise measurements of the elements. You can see the results by clicking the links below. The printouts are two pages each: