Zoom is a term that is often used in photography which signifies a change in the apparent distance between the camera and the subject. Zooming in photography is generally of two main types optical zoom and digital zoom. Both the methods use different technologies and produce different qualities in the results.
Optical Zoom vs Digital Zoom
The main difference between optical zoom and digital zoom is that optical zoom involves a physical camera lens movement, which changes the apparent closeness of the image by altering its focal length whereas in digital zoom, the pixels are enlarged at the center of the screen and the scene being clicked is magnified.
Optical zoom is caused by the physical movement of the lens of the camera. It helps to magnify the scene without affecting the quality of the photo. Optical zoom provides clearer and zoomed photos. Optical zoom works by altering the focal length of the lens, thus bringing the image closer.
On the other hand, digital zoom is a type of inbuilt processing software in the camera that the user can use to zoom in after the picture has been clicked. It is done by enlarging the pixels in the center of the screen therefore it causes a decrease in the quality of the image and less resolution.
Comparison Table Between Optical Zoom and Digital Zoom
| Parameters of comparison | Optical zoom | Digital zoom |
| Resolution | The resolution remains almost the same after the zoom | There is a decrease in the image resolution |
| Image quality | The image quality is good even after zooming in as it involves altering of focal length | The image quality is not the same and it appears a bit hazy and distorted |
| The method used | Uses physical change to adjust | Uses magnification technology to enlarge and adjust |
| Process | Presence of special button or switch that has to be pressed or rotated to have the subject either magnified or reduced in size | Presence of software that calculates new values for the pixels of the image and crops the image |
| Application | Only film cameras have optical zoom | Film cameras as well as digital cameras like DSLRs, camcorders, video cameras, mirrorless cameras |
What is Optical Zoom?
Optical zoom is available only in film cameras. The importance of optical zoom is while taking pictures through a camera and trying to get a close shot of the subject. The characteristic of optical zoom is that it makes the subject appear closer while providing the highest resolution and sharpness in the pictures. The optical zoom function has an optical zoom ratio which determines how much the lens can be zoomed.
While taking a picture, the user can get a closer view of the subject without any distortion or reduction in the quality of the image. This helps in bringing out the details of the pictures vividly which may be at a distance. Optical zoom brings the focus of the picture to one area.
The technique of zooming through optical zoom involves physically moving the camera’s lenses. The change in the focal length is done physically or manually. The zooming technique involves the lenses being physically extended to magnify the subject. The lens movement in optical zoom is controlled and monitored by the command of the user through motor control.
Cameras with optical zoom usually have a special button or switch that has to be pressed or rotated to have the subject either magnified or reduced in size. Optical zoom allows users to click pictures from a far distance yet achieve a clear and close-up image. The optical zoom lens has a range that can be changed to fit in the frame.
What is Digital Zoom?
The digital camera is available in most digital cameras and camcorders. Digital zoom can digitally enlarge the size of the scene. It can crop the entire image. Digital zoom can crop the image to a centered area. The ratio of digital zoom is almost the same as the original.
The characteristic of digital zoom is that it interpolates the result back up to the pixel dimension of the original scene and since the method involves cropping, the resolution and image quality are low and reduced. After cropping the image, digital zoom enlarges the picture back to its size. The image quality produced does not solely depend upon the megapixel of the camera.
Digital zoom allows change in the apparent angle of view of the picture. The aspect ratio of cropping the image to a central area is the same as the original and does not result back in the pixels dimension of the original image. The adjustment in the camera’s optics is done electronically in digital zoom.
The enlargement of the original pixel layout causes a reduction in the image quality as the picture is captured by the image sensor of the camera. The software inbuilt in digital zoom calculates new values for the pixels of the image and crops the image in a full-frame photo. Thus, the photo produced as a resultant is generally of lower quality than the original photo.
Main Differences Between Optical Zoom and Digital Zoom
- The photo produced by Optical zoom is of high-resolution while the photo produced by Digital Zoom is of low resolution.
- The adjustment in the camera’s optics is done physically or manually in optical zoom while the adjustment in the camera’s optics is done electronically in digital zoom.
- Cameras with optical zoom do not have any built-in software for zooming while cameras with digital zoom hands have built-in software in the camera for zooming.
- Optical zoom enlarges the zoomed photo to the original dimensions while digital zoom crops the rest of the photo and enlarges the selected area.
- Optical zoom is only present in specific film cameras while digital zoom is present in most digital cameras and camcorders.
Conclusion
Photography includes various zoom lenses which play a pivotal role in changing the focal length and creating focused images. The zoom lenses again click pictures throughout a wide range of distance from the lens to the subject. The two most common techniques are optical zoom and digital zoom.
The resultant image is different in both kinds of techniques. The former operates physically while the latter operates on software. Both the techniques have different applications and are used extensively in the domain of photography.
References
- https://ieeexplore.ieee.org/abstract/document/1341679/
- https://www.spiedigitallibrary.org/journals/Optical-Engineering/volume-43/issue-1/0000/Adaptive-optical-zoom/10.1117/1.1633570.short