Like with video cameras, digital cameras measure zoom by magnification factor. For example a camera with 3x or 3 times zoom magnifies the image by a factor of three. This does not mean that your subject will appear 3x larger than it does to the naked eye but that it will appear three times larger than it does in the unzoomed lens position. Most cameras will have a starting lens position that makes the subject appear further away that it does to the naked eye. This allows you to fit more into your shot.
Optical zoom magifies the image using lenses. This means that light is passing through curved glass which in turn makes your subject look bigger in your photo. The quality of the magnified image depends on the quality of the lenses and coatings on those lenses.
Optical zoom is the traditional kind of zoom and can produce extremely sharp images.
Digital zoom first appeared several years ago on consumer video cameras. If you ask me, this feature began as little more than a gimmick intended to fool consumers into thinking the camera had a powerful zoom. This zoom was disappointing though because the quality of it was so low that it was virtually useless.
Digital zoom produces magnification by cropping the image and up-sampling the cropped portion. The result is a loss in quality. This is because cropping reduces the number of pixels used which you can see as a blocky or blurry looking image. The more you zoom in, the fewer pixels are used to make the image and nobody wants fewer pixels.
That being said, with the advent of digital photo cameras, digital zoom has become somewhat more useful. After you have taken a photo, you can use the digital zoom to zoom up on it on the cameras screen. The reason you may want to do this is because it will allow you to bring portions of the photo you just took closer in order to make sure it is to your satisfaction. Since screens on digital cameras are pretty small, you may not notice that your subject blinked when you took the photo. Using the digital zoom permits you to look closer at the photo and reshoot if necessary. Note that using the digital zoom to zoom up on a photo after you took it does not reframe or permanently zoom up on that photo. It is just a tool to let you see it more closely.
How much zoom do you need?
Now that you know the difference between digital and optical zoom, the question is how much zoom do you need? If price weren’t a factor, some may assume that the more zoom you have, the better. Most camera manufacturers produce cameras based on this mistaken assumption.
Most people take pictures of their friends and families. When taking photos of this kind of subject, rarely will you be zooming up from far off. Actually, often the problem you will have--particularly when shooting indoors--is not having a wide enough lens to fit everyone into the picture. I would like to see more cameras produced that have lenses that start with a wider angle which would be useful in many common photographic situations.
Where a powerful zoom does come in handy is when shooting vacation photos or photos of recitals or other events where you can’t physically move closer. Most digital cameras on the market today have a 3x optical zoom. This amount of zoom fits with the needs and budget of most digital camera buyers. It is now possible to get cameras with optical zoom as powerful as 15x or more. While these can be very appealing, be aware that you are sacrificing some sharpness in order to get the versatility of a lens with such a large zoom range.
Another potential downside to buying a camera with a powerful zoom is that these cameras tend to be much larger and heavier. So if having a slim pocket digital camera is important to you, you’ll probably have to forget about getting a powerful optical zoom. Most small cameras max out at 4 or 3x zoom.
The decision about how much digital zoom you need is an easy one. Pretty much any camera being produced today has more digital zoom than you will ever need. Thus the optical zoom is truly the important specification to look for.
There are now so many different models of digital camera on the market that you should be able to find one with the right amount of zoom for you. Just remember these couple of points:
- The optical zoom a camera has is the important number to look for. Cameras will often make the digital zoom appear in big numbers and the optical zoom in small numbers. Don’t let this fool you.
- A more powerful optical zoom can reduce lens sharpness and increase the size of your camera
- You may also want to check how wide a camera goes for those situations where you can’t fit everyone into the picture.
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