The invention encompasses devices and methods used to keep the objective lens of a viewing or illuminating device, specifically an endoscope, free from obstructive fluid and dirt; specifically a device having a hollow body designed to fit over an endoscope, a transparent lens cover film that is retained within the device and that is threaded in front of the objective lens of an endoscope, thereby maintaining a clear and unobstructed transparent window in front of the endoscope lens, and an endcap configured to engage opposing edges of the lens cover film in a sealing manner.