How does a zoom camera lens work?
Mar 2023

When you're looking for a digital camera, manufacturers want to highlight specific features of their models, such high megapixel counts and sizable LCD screen sizes, in an effort to simplify the process for you.

When examining zoom lenses on a digital camera, these figures, however, don't necessarily reveal the whole story. Digital zoom and optical zoom are the two methods used by manufacturers to gauge the zoom capacities of digital cameras. The two sorts of zooms are very distinct from one another, thus it's crucial to comprehend the zoom lens. Only optical zoom, when pitted against digital zoom, reliably serves photographers' needs.

Optical Zoom

The real increase in the lens's focal length is what is measured by optical zoom. The distance from the lens's center to the image sensor is known as the focal length. The zoom increases as the lens is moved further from the camera body's image sensor because a larger area of the scene is magnified when it hits the sensor.

Certain digital cameras feature smooth zoom capabilities while utilizing optical zoom, which allows you to stop using the camera's zoom at any point along its whole length. Certain digital cameras have distinct stops throughout the zoom's length, restricting you to between 4 to 7 partial zoom positions.

Digital Zoom

To put it frankly, the digital zoom measurement on a digital camera is useless in the majority of shooting situations. Using digital zoom, the camera takes the picture, crops it, and enlarges it to provide a fake close-up image. Individual pixels must be enlarged or removed during this procedure, which could reduce the quality of the image.

The majority of the time, after taking the photo, photo-editing software on your desktop can execute tasks comparable to a digital zoom. If you don't have the time or resources to use editing software, you could use digital zoom to take a high-quality shot and then crop it to a lesser resolution that still satisfies your requirements to produce a fake close-up. Clearly, there are some situations when digital zoom is helpful.

How to Understand Zoom Measurement

When looking at digital camera specifications, both optical and digital zoom measurements are represented as a number and a "X," such as 3X or 10X. Stronger magnification is indicated by a higher number.

Remember that not all cameras have the same "10X" optical zoom measurement. The optical zoom is measured by the manufacturer between the two extremes of the lens' capabilities. The difference between the lens's shortest and biggest measured focal lengths is, in other words, the "multiplier." For instance, a digital camera with a 10X optical zoom lens would have a maximum focal length of 350mm and a minimum focus length of 35mm. However, the 10X optical zoom could only achieve a max focal length of 280mm if the digital camera also had certain additional wide-angle features and had a minimum 28mm equivalence.

In the camera's specifications, the focal length should be stated. It is typically written in a manner like "35mm film equivalent: 28mm-280mm." A 50mm lens is typically regarded as "standard," lacking both wide-angle and magnification capabilities. It's crucial to check the 35mm film equivalent number from one lens to another when attempting to compare the total zoom range of a certain lens. If you aren't looking at the proper number, it can be a little confusing because some makers publish the precise focal length range along with the 35mm equivalent number.

Final Word

Some manufacturers combine the digital & optical zoom measurements to create a larger combined zoom figure that can be shown on the top of the box when showcasing the features of their cameras.

However, you only need to pay attention to the optical zoom number, which may be included alongside a lot of other specification numbers in a section on the back of the box. To get the optical zoom measurement of a specific model, you might need to do a little searching.

Reading the small print is important when purchasing a zoom lens for a digital camera. You'll get the most out of your digital camera investment if you understand how these zoom lenses work.