• Size 1.0" (1) - Magnification 10x actual - Lens to object 1" inch (25mm)
• Size 1.5" (1½) - Magnification 6.7x actual - Lens to object 1½" inch (38mm)
• Size 2.0" (1) - Magnification 5x actual - Lens to object 2" inch (51mm)
• Size 2.5" (1½) - Magnification 4x actual - Lens to object 2½" inch (64mm)
• Size 3.0" (1) - Magnification 3.3x actual - Lens to object 3" inch (76mm)
• Size 3.5" (1½) - Magnification 2.8x actual - Lens to object 3½" inch (89mm)
• Size 4.0" (1) - Magnification 2.5x actual - Lens to object 4" inch (102mm)

Example: Bergeon 2611-2.0" eyeglass will provide 5 x magnification at 2" (51mm) distance.

Please note:
This distance is calculated for a person with 100% visual acuity; if the person's acuity is different, the focal length also changes.

The above is a guide only and "Non Swiss Made" eyeglasses will not be as accurate as Swiss Made.