The condenser lens is engraved “2/7in. 1.0 N.A. Less front lens 4/10 in. 0.35 N.A.” Iris scale engraved 1.0 to .35. The condenser lens mount is RMS objective standard, so different objectives can be utilised as condensers. The condenser also shown with an early 1″ Watson objective N.A. .28 to illustrate this. This iris wouls have to be stopped right down with this lens.
Note, 1″ objective not included, available separately for GBP 40.00.
Ask the Dealer
Ganymede Antiques, established in 1992, is based in Muswell Hill, London, U.K. We specialise in scientific instruments from the 18th and early 19th centuries, with particular interest in sundials, and drawing and calculating instruments. We are always keen to buy interesting instruments, and entire collections. We exhibit at the twice yearly International Antique Scientific Instrument Fair in London. Keith Petts can be contacted at email@example.com