What is optical vs digital zoom on a smartphone?

If someone from the earliest days of mobile phones is developed to the present day, they may mistake that one of the features we care about most on our phones is the camera.

Early phone cameras really sucked, but the ability to carry cameras wherever you go quickly made them hugely popular. As a result, manufacturers have poured a great deal of fortune into the development of cameras and now we have phones with cameras that can make professional cameras a big buck. At least under the right conditions.

One thing that relatively few smartphone cameras have, however, is optical zoom. However, you will start to see it on more newer phones as time goes on. This is the right time to discuss optical and digital zoom.

What is “Zoom”?

You probably already know what a camera zoom is. At least, you know what it does. “Zoom” is a function that makes distant subjects in your photo appear up close. An effect on a photo is basically adjusting it by making the object or person fill the space more.

There are different ways to achieve this effect, but most smartphone cameras use a method called digital zoom. To understand how optical zoom is different from the digital zoom method we are currently using, we will first have to explain digital zoom as it is currently used in the vast majority of people. phone.

Everyone does it: Digital Zoom

Digital zoom is like cropping and resizing a photo in an app like PhotoShop. The main difference is that you are going live, while taking a photo or recording a video. So what’s the big deal? It’s all down to pixels. That is the origin of “digital” in digital zoom.

When you enlarge a digital image, it becomes more “pixelated”. That’s because you have a fixed supply of pixels. The only way to zoom is to make the pixels bigger. The image becomes grainy, noisy, and ends up with a low fidelity image.

That may sound a bit catastrophic for a smartphone, but various tricks have been developed by smartphone manufacturers over the years to make the effect of pixels on a well-zoomed image. less digital becomes more of an issue. Because modern phone cameras have sensors capable of capturing more pixels than most people normally need. So you can crop to a fraction of the full sensor resolution without any loss of quality.

That’s perfectly fine if you want to take a photo suitable for social media, but if you want to take a photo at the full resolution of your camera, you can’t zoom in on any part of it without losing your focus. detail.

Most people probably don’t care about having large, full-resolution images that can’t be uploaded to FaceBook or InstaGram in their true quality. However, more and more people are taking smartphone photography very seriously. Which means there is a market for more advanced solutions. That’s where optical zoom comes into the picture.

Pun fully intends.

Bending light: Optical zoom

Optical zoom is simply a zooming method that uses light to magnify an image. It works like a magnifying glass, bending light through an optical medium (lens) to create a larger image.

In a dedicated camera, such as a DSLR (digital single-lens reflex camera), you have large lens assemblies that can be zoomed by physically moving the lens back and forth. This changes the focal length between the lens and the camera sensor. Project a magnified image onto the entire sensor.

As you can tell from the way it works, this means that the magnified image projected through the lens will cover the entire sensor with full resolution under light. That means the magnified image has exactly the same detail as the full image on a digital zoom-only camera. It’s true lossless image magnification.

Optical zoom is difficult in smartphones

To achieve optical zoom on a smartphone is not a trivial matter. You really can’t have a large motorized lens assembly on the back of a phone. Although, this was actually attempted. For example, the Samsung Galaxy S4 Zoom is essentially a smartphone with a compact digital camera glued to the back. Have a look here:

Obviously it’s not something you can put in your pocket, which is why this approach never really worked. Instead, modern smartphones simply stick a series of cameras on the back of our phone. Each camera has a different focal length range, so when you add all the cameras together you get an optical zoom range.

This is not the same as having a large telephoto lens on a DSLR, for example. That’s because you can move the focal length of the telephoto lens to focus images at different zoom levels onto the same sensor. The problem is that most multi-camera smartphone setups have different sensors for each lens. Primary cameras usually have the largest sensor with the highest pixel count. With wide-angle and telephoto cameras with smaller, cheaper sensors.

Doesn’t this negate the whole point? That’s true in a way, but the multi-camera setup still offers the best high-quality zoom range on a phone. Engineers have devised a way to combine these different approaches to magnify something larger than the sum of its parts.

The Best of Both Worlds: Combined Zoom

The so-called “composite” zoom system uses the optical capabilities of the onboard cameras along with digital zoom and something known as “computed imaging”.

Computational photography refers to a set of software techniques that use artificial intelligence and other fancy mathematical methods to alter and enhance the images a camera can capture. For example, artificial intelligence can increase the resolution of an image by “imagining” what the image would look like at a higher resolution.

It sounds like magic, but it actually works pretty well in most cases. Software techniques like these can also help combine different images from the onboard cameras to enhance image detail at the higher end of the optical zoom range. Even when digital zoom comes into play, all these image data sources and intelligent software algorithms can produce some stunningly beautiful images.

Should you care about optical zoom on a smartphone?

High-end smartphones like iPhone 12″ has a good optical zoom range. It’s not really “telephoto” by any means, but you can generally expect a 2x to 2.5x increase in image size with no pixels. This is perfect for typical use cases like taking a picture of something reasonably close that you can’t get any closer.

It’s definitely a great feature to have, but the vast majority of users will be completely satisfied with the digital zoom feature. Especially when enhanced with a nice artificial intelligence doll. If phones start to offer over 2.5x optical zoom range at the same resolution as the main sensor, it’s time to sit up and take note. However, at the time of writing, it’s not a feature that affects your purchasing decision.

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