As a complete photography beginner or a newbie novice, it can be easy to get bogged down in photography terms and end up totally confused. If you’re about to buy your first ‘proper’ camera you are in need of definitions for optical and digital zoom, so keep reading!
We all know what zoom means – especially with the amount of camera equipment around us and the increasing quality of smart phone cameras. But to understand how zoom works and can be compared, you need to think about zoom as magnification. A camera with 10X zoom when zoomed in all the way will make the image 10X bigger than you can see with your eyes standing there, simple right? If only!
What is optical zoom?
Optical zoom was originally the only kind of zoom, found on film cameras before the digital age. It is simply zooming in and out of your subject using the camera lens.
By zooming with a lens what you are actually doing is changing the focal length of your lens. If you look through a camera and the subject looks life size then the magnification is zero, and the focal length is about 50 mm. If you zoom in then the focal length gets larger, lenses that can zoom in really far are known as telephoto lenses. Likewise if you zoom out further than life size, making the subject seem further away and smaller than in real life, the focal length is lower than 50 mm. These kinds of lenses are called wide angle lenses.
The higher the optical zoom is on the camera specification then the closer it can zoom in. All digital cameras will have optical zoom, but only very recently is optical zoom starting to appear in mobile devices.
What is digital zoom?
Digital zoom was invented with digital cameras. It is used to make the subject seem more close up, but it is not actually ‘zooming’ in the same way as optical zoom works, it only simulates it with your camera software.
What it actually does is just crop and enlarge the image back to size. You are effectively only zooming in on the already created photo, creating the effect of zoom, not zooming into actual detail – imagine stretching the image out to make it bigger on a computer and then cutting out the same size as the photo the bit you wanted to focus in on.
Using digital zoom results in loss of image quality and resolution, so your photo will look blurred the same way that using a low megapixel camera will do. Remember, your zoomed image doesn’t contain any extra pixels, as most often pixels are larger to make the zoomed portion of the image larger – hence why the image will have less detail and be blurred. This is the most common type of zoom on a phone camera.
Optical zoom vs. digital zoom
When it comes down to optical vs. digital zoom, always compare optical with optical, you should rarely use digital zoom and most cameras have a feature to turn it off. As optical zoom is not megapixel or resolution dependent – the number of megapixels with image is captured with never changes whether you zoom in or not – your images will always be high quality. You can achieve the same effect as digital zoom with image editing software later if you need to without losing any of the image quality in the original.
Image credit: Dave Farmer’s blog
Neither of these are the same as total zoom, which is both added together, and isn’t an accurate description of the zoom power, so ignore this when looking at cameras.
It doesn’t mean you should buy a digital camera without digital zoom, you’d have a hard time trying to find one without it! Digital zoom is not the worst feature ever. It can be useful if you are trying to capture action shots such as a sporting event, or if you can’t or won’t use image editing software later to zoom further. The important point is to know when not to use it – for example mountain scenery isn’t going anywhere in any kind of hurry, so don’t use it for landscape shots.
Good camera zoom
One final point to remember is that when a camera says it has 10X zoom, it doesn’t always mean it will zoom 10X closer. Part of the zoom range of a camera normally includes a wideangle range – it doesn’t start zooming from lifesize, it zooms from further out, so you get less magnification than you expect.
Choosing a good camera for your zoom needs shouldn’t be difficult. Point-and-shoot cameras come with lenses built in, so the zoom they have is what you get. DSLRs on the other hand have a huge range of lenses available so you can change your zoom according to the lens you use, you can even chose super-zoom lenses with up to 30X zoom or ultra wideangle lenses (great for scenic shots).
Don’t forget once you’ve got that perfect shot to print and display it on a photo canvas!