The Farnsworth Lantern has been accepted in many occupational applications. Modern instruments purporting to be equivalent were inevitable given the ubiquity of its use. The OPTEC900® (Stereo Optical) has been validated and adopted as an acceptable substitute, although the fail rate is slightly higher. The Farnsworth Flashlight (Gulden Ophthalmics) has been marketed without validation. The color and luminous intensities of the three lanterns’ stimuli were measured using a Topcon SR-3 telespectroradiometer and compared with Farnsworth’s recommendations. The OPTEC900® chromaticities comply with Farnsworth’s recommendations, but the luminous intensities are rather different. The Farnsworth Flashlight differs from the Farnsworth Lantern in both chromaticity and luminous intensities. A cheap and portable equivalent to the Farnsworth Lantern is a highly attractive product. However, the Farnsworth Flashlight is significantly different in construction from the Farnsworth Lantern.
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