Well, A lens which has a variable focal length that can be set manually or remotely. Unlike the varifocal lens, if the back focus is correctly set, the image should stay in focus as the focal length is altered.

Zoom lenses are often described by the ratio of their longest to shortest focal lengths. For example, … Read more

First you need to make sure they are flying ants and not termites. In either case, they themselves are harmless. They are released to try to establish a new colony. You need to find the location where they emerged from. If they are ants, try baiting to kill the queens (gel baits are the best), … Read more

Robert Falcon Scott.
Scott reached the South Pole on January 17, 1912, only to find that Norwegian explorer Roald Amundsen had been the first one there 34 days before. Scott and his party perished on the return journey.