ESA Certified Alarm Technician Practice Exam

What type of lens can change focal lengths within a set range?

1. Fixed

2. Varifocal

3. Wide-angle

4. Fish-eye

The correct answer is: Varifocal

A varifocal lens is designed to change focal lengths within a specified range, allowing for adjustable zoom capabilities. This type of lens provides versatility in framing and capturing different types of scenes without needing to switch lenses. Unlike a fixed lens, which has a single focal length and cannot be adjusted, a varifocal lens allows the user to zoom in or out to achieve the desired composition or field of view. Wide-angle lenses usually have a fixed focal length but provide a broader field of view than standard lenses, while fish-eye lenses provide an ultra-wide perspective with significant distortion and also have a fixed focal length. Therefore, the unique feature of a varifocal lens is its ability to adjust the focal length within a defined range, catering to various shooting requirements. This adaptability makes it particularly useful in surveillance, photography, and videography, where varying distances to subjects can be encountered.