Everest Interscience’s VARIO-ZOOOM™
These include the following: a SKY-SPY™ System (U. S. Patent No. 4,420,465), VARIO-ZOOOM™ Field-Variable-Focus System (U. S. Patent No. 7,355,178), and TTL/SLR Intra-Optical Light Sighting System (U. S. Patent No. 4,494,881).
These features combined provide for the most accurate possible infrared thermometers for measurements of outdoor targets.