Martin Brenner's, Pilot Balloon Resources
Chinese Pilot Balloon Theodolite
This theodolite model was purchased from a dealer in China in 2005. It may have been produced in 1971 as the large 71 indicates, a recent post on Ebay from a Chinese seller implied that the 71 relates to the model number and not the year of manufacture. It is 13 inches tall and has very large optics operating at 30X. The vast majority of balloon theodolites are 20X and utilize smaller optics. The finder scope is 6x rather than the common 4x.
Like the Russian and other Chinese models on this site it has complex optics that allow the viewing of the circles in the main eyepiece focused at infinity like the balloon. This model also has a compass hidden under a cover as shown below.
This theodolite is one of the modern designs (for a non digital) theodolite. It uses friction driven glass circles which are read through the eyepiece. Its optical path is similar to the ATK-2 The verniers read directly to .1 degree and they are set up so they can be read very rapidly. This theodolite is quite large and heavy it features a large 60mm main objective (30 power), 16mm finder scope (6 power) and gun site. It also includes a compass, internally switched filters, a lighting system, or mirror for daytime use tools and a metal case with straps for carrying on the back.
A unique (shared with the AWT instrument and the later CFJ/weathermeasure) aspect of this theodolite is that the reticule assembly is mechanically connected to the body of the theodolite not to the eyepiece tube. This allows the cross to maintain its vertical orientation regardless of the elevation of the telescope. It resembles the CFJ-IIB theodolite but is much larger, heavier and has the addition of an internal filter set and hidden compass as well as higher power. This instrument was represented by the seller as military surplus and not intended as a commercial product for export.