Finescale ® Magnifying Comparator Reticles

Since at least 1965, the Finescale® company has been producing high-quality optical tools for “machinists, inspectors, engineers, toolmakers, draftsmen, scientists, jewelers, printers, model makers and more.” Their Magnifying Comparator is a pocket-sized loupe with adjustable focus which rests flat on surfaces and which allows for interchangeable reticles for measurement and comparison. Because of the tight tolerances of the Comparator’s fabrication, it guarantees accurate visual measurement down to 1/1000 of an inch. The interchangeable reticles come in a wide variety useful for various trades and applications. Devised by microfilm specialist George Francis Gray, the following text describes the manufacture of these reticles:

Finescale reticles are manufactured photographically using a precision microfilm camera. Every reticle is an original negative photograph from a master 20 times full size. The masters are prepared on a precision coordinatograph which maintains an accuracy of .001″ in 10 inches. The master base material is .007 thick mylar. The reticles are checked for accuracy on a batch basis using a 120 power microscope with a .0001″ reading micrometer stage. Calibration of the micrometer is accomplished with a .500″ gauge block that is certified by the National Bureau of Standards. Camera set up, focus, temperature and humidity further effect finished reticle accuracy. As a result we can state an accuracy of +/- .0005″ full scale for all or our reticles. The Reticle itself is of a polyester base insuring good temperature stability. Finescale reticles are intended for use in the Finescale Magnifying Comparator ONLY [emphasis added by Finescale].

Finescale No. 10 Pocket-Sized Magnifying Comparator

The Fincesacle Comparator is LoupeBlog’s mascot.

To this day, the Comparator is available for purchase along with the wide range of reticles. Below is the Finescale line of reticles. You can visit their website and make inquiries for purchase here.

Text and catalog facsimiles reproduced from Finescale website.