Zooming is the process of using your camera to bring the subject visually closer. There are two different types of zoom, however: optical and digital—and one is considerably better than the other. In this article, we explain why optical zoom is better than digital zoom.
Although many digital cameras offer both optical and digital zoom, optical zoom generally produces better image quality. With optical zoom, the lens changes its focal length, making the subject appear larger on the image sensor. Digital zoom, by contrast, merely enlarges part of the captured image.
But first, let’s take a closer look at optical zoom (pun intended) before explaining the difference between optical and digital zoom.
A camera lens consists of several glass or plastic lens elements. These elements are arranged in different lens groups, which collect the incoming light and focus it on the image sensor.
In an optical zoom lens, different lens groups move in relation to one another. This changes the focal length and angle of view. Your subject appears larger or smaller on the image sensor while the sensor’s full resolution remains available. Sharpness and maximum aperture may vary slightly across the zoom range.
Not true zoom
Digital zoom is not optical magnification. The lens’s focal length does not change. Instead, the camera uses a smaller portion of the sensor image and then enlarges it to the desired image size.
Basic digital zoom is largely comparable to cropping and enlarging a photo afterwards. Because fewer original pixels are used, fine detail is lost and softness and image noise can become more noticeable.
Some modern cameras and smartphones use additional image processing to limit the loss of quality. This can produce a better result than a simple crop, but it will usually not deliver the same level of detail as genuine optical zoom.
If you have sufficient resolution, you may therefore prefer to shoot without digital zoom and decide on the crop later. A large screen allows you to judge more precisely which parts of the photo you want to retain.
The complete original image also remains available, giving you more freedom to adjust the composition afterwards. Bear in mind, though, that cropping also reduces the number of pixels left in the image.
Resolution matters
Why is this important? When you zoom digitally, you use less of the original image information. This leaves less resolution and can cause fine detail to be lost.
A digitally zoomed photo may still be suitable for online use or a small print, particularly if the original photo has plenty of megapixels. With larger prints, the loss of quality generally becomes apparent sooner. The final quality depends on the number of remaining pixels, the print size and the viewing distance.
If your camera has no optical zoom, you can try moving closer to your subject. This may produce a better result than using a great deal of digital zoom. Walking closer and zooming optically do not produce exactly the same image, however: moving the camera also changes the perspective and therefore the relationship between the subject and the background.
How do I know whether my camera uses digital or optical zoom?
To find out whether a camera has digital or optical zoom, simply look at the camera body. A compact or ‘point-and-shoot’ camera—a basic pocket-sized model—will probably have ‘optical zoom’ printed next to the lens.
If it does not say ‘optical zoom’, the camera probably does not have it, because optical zoom is a selling point and manufacturers are unlikely to omit it if the camera offers the feature. Another clue is whether the lens retracts: a lens that extends from and retracts into the camera when you switch it on probably provides optical zoom. But a lens that does not extend may still be an optical zoom lens, as some zoom lenses remain in a fixed position.
If in doubt, consult your camera manual, or simply look up your camera model online and check the marketing material. If you do not yet have a good internet plan, it is worth comparing a fibre broadband plan online with your current package.
Manufacturers almost always state which type of zoom a camera has, but beware of marketing copy that presents digital zoom as an advantage. It is not (as you now know), although it may be promoted as one.
Some cameras simply do not have digital zoom, so do not worry if you cannot find any reference to it in the manual. It is far more likely to be a feature of point-and-shoot or compact digital cameras. If the manual does not mention it, your camera does not have the feature.
If you are using a camera with no optical zoom at all, first try simply walking closer to your subject
Cameras with interchangeable lenses may also have a digital zoom function. With these cameras, you would normally zoom optically by using a zoom lens or fitting a lens with a longer focal length. Digital zoom may additionally be available for stills or video, but this varies by camera model.
Turning off digital zoom
Some cameras combine optical and digital zoom. When you reach the end of the optical zoom range, the camera may switch automatically to digital zoom. If you do not notice this, the final image quality may disappoint. Check the manual or your camera’s menu to see which zoom setting is active.
On many cameras this can be adjusted, meaning that you can decide whether and when digital zoom is used—and you may even be able to turn it off entirely.
With a DSLR or mirrorless camera, the angle of view is determined primarily by the lens being used. Some models nevertheless offer digital zoom or a similar magnification function as well. Check the camera menu or manual rather than assuming that the feature is absent.
Many modern smartphones combine several cameras with different fixed focal lengths, such as ultra-wide, standard and telephoto cameras. At certain zoom settings, the phone therefore switches to another camera. Between these settings and beyond the telephoto camera’s range, digital zoom and computational image processing are generally used.
Whenever possible, use one of the smartphone’s fixed optical zoom settings. As you zoom beyond the optical range, progressively more detail is generally lost. If you cannot move closer to your subject, you can use digital zoom if necessary or crop the photo later.
Remember
When buying a camera, it is wise to look carefully at the optical zoom range and any digital zoom functions. A large optical range can also be found in a fixed-lens camera, such as the Sony RX10 V with its 24-600mm lens.
Manufacturers may combine the optical and digital zoom ranges and present them as one large overall zoom range. A camera with 6x optical zoom and up to 6x digital magnification, for example, may be advertised as offering up to 36x combined zoom. Only the first 6x is achieved by the lens, however; after that, the image is enlarged digitally. When comparing cameras, therefore, focus primarily on the optical zoom range.
It may be one of the easiest ways to get better photos: simply do not use digital zoom. You will immediately get better, cleaner photos by turning that option off and zooming optically, or by simply moving closer to your subject.
