What is Optical Zoom and How is it Different from Digital Zoom?

What is Optical Zoom and How is it Different from Digital Zoom?

GLOBAL DIGITAL TIMES | What is optical zoom and how is it different from digital zoom? Optical zoom uses the camera lens to magnify images without losing quality. Understand how it works and how it compares to digital zoom.

The difference between optical zoom and digital zoom is that the former uses a set of lenses to produce a true approximation, which underpins image quality. In digital, estimates are made by software. Next, understand how different types of zoom work, their advantages and limitations.

How optical zoom works

Optical zoom is a mechanical process that drives a camera's internal lens array to produce a wide focal length. The greater the focal length applied to a zoom lens, the closer the subject being photographed or filmed will be.

In the context of DSLR and mirrorless cameras, an optical zoom lens (zoom lens) has a minimum and maximum focal length. This feature makes it different from a prime lens, whose focal length never changes.

To allow the focal length to be shortened or extended, telephoto zoom lenses rely on an array of lens elements of varying shape.

According to the control applied, the lens element changes position to create an image magnification effect. Then, the light captured by the lens goes to the image sensor to produce photos or videos.

On the phone there is also optical zoom, but in a limited way. Because of this, some models have hybrid zoom, a method that combines a lens approach with digital zoom (software-generated zoom) to achieve an artificially greater range.

How does optical zoom work on mobile?

Since cell phones are such compact devices, there are physical limitations to moving the lens. Therefore, many smartphones use multiple cameras with different focal lengths to implement optical zoom.

Such is the case with the Samsung Galaxy Z Fold 4. The device has a telephoto lens with a focal length three times that of the main camera. Thus, if the user enables the 3x option in the photos app, the zoom camera will be triggered instead of the default camera.

In 2022, Sony introduced its first “true” optical zoom phone: the Xperia 1 IV. This model has an optical assembly with a focal length of 85-125mm which allows magnification from 3.5 to 5.2x in relation to the 24mm wide-angle camera also present there.

Some smartphones, such as the Galaxy S22 Ultra and Motorola Edge 20 Pro, feature a periscopic camera for optical zoom. This system overcomes the lack of internal space by positioning the lens perpendicular to the phone.

Advantages and limitations of optical zoom

Optical zoom is often considered better than digital, but it also has limitations. You can expect the following features:

Better image quality : image composition with optical zoom does not result in a loss of sharpness, unlike what can happen with digital zoom;
Sensor-free : Optical zoom does not require a high megapixel sensor to produce sharp images;
Wide magnification capacity : some zoom lenses have so many degrees of approximation that they can cover subjects tens of meters away;
Physical limitations : on mobile phones, optical zoom is quite limited because there is not enough space for the distance between the lenses. Zoom lenses for DSLR and mirrorless cameras can be large and heavy;
High cost : Optical zoom is expensive to implement because it is based on a sophisticated set of physical components. On a DSLR or mirrorless camera, a zoom lens can cost tens of millions of rupiah.

How digital zoom works

Digital zoom uses a software feature to crop images. Then there is enlargement of the cropped area.

This solution was implemented on cell phones and simple digital cameras to compensate for the lack of optical zoom.

However, digital zoom degrades image quality as magnification increases. This is because when the crop is enlarged, gaps between pixels appear.

To fill in these spaces, the software performs interpolation, that is, creates pixels from the pixels that make up the original image. Pixel interpolation reduces sharpness, and if too intense results in a pixelated image effect.

Deterioration with digital zoom can be reduced or avoided when zooming in is applied to high-resolution images. In this case, the number of pixels resulting from the interpolation is not large.

Advantages and limitations of digital zoom

Digital zoom can be the best solution for those who have portable equipment and don't need very high resolution images. You can expect the following features:

Implementation on small devices : digital zoom is a solution for portable equipment due to size limitations or cost controls and does not have optical zoom;
Easy to use : digital zoom can be applied with a dedicated button on the camera or by pinching gestures on the smartphone screen;
High magnification capacity : digital zoom can produce a high approximation effect, especially on cameras with larger megapixels, although excess can be detrimental to image quality;
Possible loss of sharpness : Pixel interpolation can cause noise and reduce image definition. Not exaggerating the crop level or magnification prevents loss of sharpness from accentuation.

Hybrid Zoom: Combines features on smartphones

Hybrid zoom is a method that uses digital zoom to magnify pictures taken with optical zoom. This approach is useful when the goal is to get closer than is achieved with a telephoto lens.

There are cases of phones that promise 100x zoom to make it possible to photograph the moon. The Samsung Galaxy S23 Ultra is one of them. The device has a periscope lens with 10x optical zoom, but the spatial zoom mode uses software to expand the reach by up to 100 times.

Phones like the Huawei P50 Pro and Xiaomi 10 Pro also launched with 100x hybrid zoom.