Scott's Photographica Collection

Monner Exposure Meter


The Monner exposure meter has to be one of the most innovative and unusual exposure measurement devices created.  This type of meter is called a pupilometer - that is, a device that measures the size of the eye's pupil.  Pupilometers are currently used in the medical and law enforcement fields.  But apparently only two different pupilometer designs were ever marketed to photographers for photographic use.

The patent for the Monner meter was granted to Ray J. Monner of Rapid City, South Dakota USA in 1939.  Follow this link to view the Monner patent documents.  This meter, marketed in the 1940s probably did not break sales records, and is somewhat difficult to find today.  It was manufactured by Black Hills Industries Inc. of Denver, Colorado USA.  At an earlier date the company was located in Rapid City, South Dakota.

Two avid exposure meter collectors provided me with helpful information on the Monner meter and pupilometers.  Thanks to Mr. Richard Holzman and Mr. Lester A. Pfeffer.    

Monner Exposure Meter Front View
Front of Monner Exposure Meter

The Monner meter is constructed of two sheets of glass clamped front and back by a thin metal frame.  Looking at the front of the meter, beneath the glass, you'll see a card with exposure times and apertures laid out in a table format.  There are drawings of different sized pupils at the top of each column.  A silver mirror is located above the pupil drawings.  The mirror does not look reflective in this scan, but it is brilliant in normal light (I should have dusted it).

To use the meter, hold it at eye-level and look at the scene to be photographed.  Glance into the mirror and compare your pupils to the size chart, selecting the closest match.  Now read down that column to select a shutter/aperture combination.  That's all there is to it.

The meter is calibrated for film with a Weston speed rating of 24.  The back side of the meter gives directions for adapting the exposure table to other film speeds.  Settings are also given for cine film, in both black and white and Kodachrome, running at 16 frames per second. 


Monner Exposure Meter Back View
Back of Monner Exposure Meter

The Monner meter is compact, light and easy to carry.  It measures 2 1/4 x 4 x 5/16 inches.


Monner Exposure Meter Case
Monner Exposure Meter Case

I am told a pupilometer invented by Charles Ansel Watrous of New Haven, Connecticut USA was also marketed.  The Watrous patent was granted in 1934.  I haven't seen an example of this device, but from reading the patent application, I can say it is much more complex than the Monner meter.  Follow this link to view the Watrous patent documents.

If you have a Watrous meter for sale, I'd like to hear from you.


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Page created November 13, 2001; updated December 20, 2020