Ultimate Proportion Wheel Calculator, Inch (Fractional) 7.5" Diameter - Model CNF-1201

The ultimate in dial slide rule type proportion calculators. The Gaebel Scale was designed and is produced by GEI International, Inc. (formerly Gaebel Enterprises, Inc.).

The Proportion Wheel can be easily held in the left hand and the dials and cursor turned with the right hand.

Two heavy duty eyelets permit the mounting of the calculator to a camera , copy table or other item.

There are four proportion scales for reproduction size, original size, percentage of original size and number of times of reduction.

Set any one of the scales and read off the dial the value of any of the others.

All linear size scales are from 1/16" to 100" with from 1/16" to 1" in 1/64" increments.

Scales are also featured on the calculator for quick conversions between picas, points, decimals and agates.

An incorporated time exposure constant system calculates the correct camera lens aperture for camera reductions and enlargements both for line copy and halftones. For example, if F16 for 45 seconds is the corrct time at one size, 45 seconds is also the correct time for all other apertures shown on the calculator.

Apertures are indicated in F22, F32, F45, F64 and F90.

The calculator is 7.5" (190.5mm) in diameter.

Historical Model #s: 1200, 1201, 1204, 1205, CNF-1200, CNF-1201, CNF-1204, CNF-1205, CNF-1200A, CNF-1201A, CNF-1204A, CNF-1205A