Optical Zoom vs. Digital Zoom (Page 3 of 3)
Notice how blocky the picture is? Can you see the individual pixels? We’re getting this lousy quality because the camera is using only a portion of its sensor. My sensor still sees the entire school, but it has discarded all the parts of the picture that aren’t the flag To be fair, I should confess that I’ve deliberately simulated a worst-case, very low resolution situation to more clearly illustrate the difference. Digital zoom will always degrade the quality of the image, but it may not always be as obnoxiously bad as I’ve illustrated here.
A Word about Camcorders
I’ve spoken mostly in terms of digital still cameras thus far, but the optical vs. digital zoom distinction holds true for digital camcorders as well. Just like digital still cameras, digital camcorders have lens components that can be zoomed in or out to control an optical zoom. And, just like digital still cameras, many digital camcorders can also selectively scale down which parts of their sensor chips are being used to create a digital zoom effect. Some digital camcorders even take this digital zoom to extreme levels. Here’s the marketing label from my camcorder boasting a whopping 700x digital zoom capability.
Now that you understand how digital zoom works, I hope you can envision what a 700x digital zoom would do to the picture quality of a camcorder if we chose to zoom all the way in. We’re talking about a seriously blocky, low-quality video image at 700x.
Here are a few recommendations to help you deal with zooming:
- When selecting a digital camera, compare just the optical zoom capabilities of the different models you’re considering. As we’ve seen, optical zoom can get you closer to your subjects with much less loss in image quality. Most consumer digital cameras these days come with a 3x or 4x optical zoom, though some go up to 6x or even 10x.
- If your camera doesn’t have digital zoom capability, don’t worry. In fact, most high-end digital cameras do not come with any digital zoom capability whatsoever. Any decent photo editing program on a computer can achieve the same effect by cropping. Cropping allows you to draw a box around only the part of the picture you want to keep and throw the rest away. The effect works exactly the same way digital zooming does but it gives you more control.
- Most digital cameras will use their optical zoom capability first and then, if you continue to zoom in, they’ll go the rest of the way using digital zoom. If you want to avoid blocky, pixilated pictures, most digital cameras give you the option to shut off digital zooming. This will limit your zooming range to just your camera’s optical zoom capability, but it will guarantee that you’ll never ruin a picture with digital zoom.
- Digital zoom isn’t necessarily a bad thing. If you like the convenience of zooming way in on your subject and you don’t mind some loss in image quality, then by all means use your camera’s digital zooming capability. It can be a very convenient feature and, if you don’t go too far with the digital zoom, the image quality may still be good enough for your needs.