Zoom is definitely a word you’ve heard, but do you know what the terms “digital zoom” and “optical zoom” mean? I will discuss the distinctions between digital and optical zoom as well as their benefits in this article.
What is meant by zoom?
In photography, “zooming in” means enlarging the subject in the frame without having to move forward. On the other hand, “zooming out” means going in the other direction and making the subject smaller in the frame. This is made possible by what is called zoom lenses. With them, you can change the focal length without having to use another lens.
On a DSLR or mirrorless camera, zooming is done either by turning a ring on the lens or by pushing and pulling on the lens barrel. On most compact cameras, zooming is done by turning a dial on the top of the camera. These movements adjust the focal length of the lens so you can zoom in on the scene.
However, not every zoom is the same! The development of digital technology has changed a lot and so the concept of “zoom” is now a bit more complex.
Various zoom methods
As mentioned above, since the development of digital photography, there are two different types of zoom: Digital zoom and Optical zoom. With optical zoom, the actual distance between the camera sensor and the subject is changed by adjustments to the lens. Digital zoom on the other hand, enlarges a certain area of the image while reducing the megapixels in other areas to compensate. This results in a deterioration of image quality.
Digital vs. Optical Zoom – What’s the difference?
What is optical zoom?
Optical zoom is caused by a physical rotation of the camera lens that changes the focal length of the lens. As you zoom in, the lens moves away from the sensor, making the subject appear larger/closer.
What is digital zoom?
Try to think of digital zoom as a kind of image editing software. It enlarges the pixels in the center of the image and crops the edges. This makes the object in the center of the image appear larger. Unfortunately with digital zoom, you have to expect a degradation of resolution and image quality.
With which lenses you can zoom?
Optical zoom can only be achieved (physically) with an appropriate lens, whereas digital zoom works with all modern cameras such as compacts, DSLRs, mirrorless and video cameras, smartphones, etc. with appropriate technology.
With which lenses is an optical zoom possible? There are two basic types of lenses: Fixed focal length lenses and zoom lenses.
- Fixed focal lengths have a fixed focal length that cannot be changed. They are faster and sharper.
- Zoom lenses contain multiple lenses and can therefore be set to different focal lengths. They are more flexible than fixed focal lengths but do not react as quickly.
The designation of a lens is based on its focal length. If this consists of a single value (e.g. 50 mm), it is a fixed focal length. If, on the other hand, a range such as 15-35 mm is given, you are holding a zoom lens. This means that the lens can be set to a focal length of 15 mm, 35 mm, or anything in between.
Whether you’re using an analog or digital camera, you can’t use optical zoom with a fixed focal length! This is simply because the focal length cannot be changed.
The right zoom lens
On the current market, you will find a huge range of different zoom lenses. Not all of them have the same capabilities! When choosing the perfect zoom lens for you and your camera, you should pay special attention to the following two points:
1. Focal length
The focal length value refers to the apparent proximity of the subject to the camera and is expressed in millimeters. The two extremes on the focal length scale are telephoto lenses and wide-angle lenses.
A telephoto lens is any lens with a focal length of at least 60 mm. The longer the focal length, the narrower the angle of view and the greater the magnification. Telephoto lenses are therefore particularly suitable for taking pictures from a greater distance, e.g. wildlife.
Exactly opposite to the telephoto lenses, the wide-angle lenses have a short focal length of 35 mm or less. They are especially popular for landscape photography. If you use a lens with optical zoom, you have all focal lengths from wide-angle to telephoto available in one model.
2. Zoom factor
The amount of zoom in either direction depends on the minimum and maximum focal length of your lens. The ratio of these two values is called the zoom factor. This value often appears in advertisements for compact cameras and is indicated there as a number + letter X. Lenses with a particularly high zoom factor are also called superzoom lenses.
A high zoom ratio does not automatically mean that you can magnify your subject extremely. This value is more about the flexibility of the lens than its magnification capability.
Although optical zoom is mostly analog, nowadays it also includes some digital features. Some digital cameras have an additional feature called “smooth zoom” that allows the focal length to be adjusted even between values. Especially long zoom lenses can be affected by camera shake. Digital cameras try to compensate for this problem by using an image stabilizer.
Digital vs. Optical Zoom – Which is better?
This question is relatively easy to answer: Qualitatively, the optical zoom is the clear winner. So if you’re looking for a high resolution that stays with you even when you zoom in, I’d recommend optical zoom. Most professional photographers do not use digital zoom at all and prefer to enlarge and crop their RAW files after shooting with an editing program.
The digital zoom options depend on the resolution of your camera. A newer variant is the Intelligent Zoom: it reduces the image so that it appears of higher quality when enlarged. Despite its qualitative shortcomings, the digital zoom also has some advantages:
- Better overview of the scene when you are a little further away. This is especially true for moving objects.
- For example, on a smartphone, you don’t have the option of optical zoom. So there digital zoom is a good alternative!
Smart, Safe and Intelligent Zoom
In the search for a variant of the digital zoom with higher quality, various camera manufacturers have found a similar solution. This new zoom technology has the following designations, depending on the brand:
- Smart Zoom (Sony)
- Safe Zoom (Canon)
- Intelligent Zoom (Panasonic and others)
To summarize, let’s talk about Intelligent Zoom (iZoom for short). The iZoom tries to find a compromise between magnification and image quality and accordingly works without interpolation. However, the function is only available if the image is smaller than the actual maximum achievable image size.
If your digital camera can produce a 12 MP photo, the iZoom will only work if you save the image as 7 MP or smaller. In terms of how the iZoom works, this means that the MP resolution is reduced when zooming, or the central area of the image is cropped out.
Let me explain this a little more practically. So you have a 12 MP camera and you decide to save all images as 10 MP. In doing so, you give up 2 MP of image data that the sensor captured but now has to “dispose” of.
Unlike the traditional digital zoom, the iZoom works without interpolation and re-magnification to 12 MP, since you wanted to save it as 10 MP anyway. So the result is a slightly smaller image in original image quality with a “simulated” zoom effect. Just note that the magnification in post-processing is limited to the standards of a 10 MP photo.
Conclusion: Digital and Optical Zoom
Once again briefly summarized the basics on the subject of digital and optical zoom:
- Optical zoom changes the focal length of the lens and thus the distance of the object to the camera sensor.
- With digital zoom, the pixels in the center of the image are enlarged, but others are cropped out. The image quality deteriorates.
- Optical zoom only works with a corresponding zoom lens, not with a fixed focal length!
- The optical zoom is far superior in quality compared to the digital zoom.
- A slightly improved version of the digital zoom is the iZoom, but even that falls short compared to the optical zoom.
So my recommendation is: try to use the optical zoom if possible if you want to achieve a really satisfying result. Comparing optical and digital zoom at all is actually not very useful. But if you have the choice between traditional digital and iZoom, choose the iZoom.
I hope this article has helped you understand the difference between digital and optical zoom. Feel free to share your feedback, questions, or tips on the topic in the comments!