While smartphones have put a large dent in the compact camera market, tens of millions are still sold, and I often get asked about what features to look for when purchasing one. Headline numbers in ads often include not just resolution, but zoom range. Some models, like the Lumix DMC-ZS50 I'm currently testing, offer ranges up to 30:1 (effectively a 720mm telephoto lens at the long end). It is really tempting to think, "Wow! Why not get one that does that?" However, there are tradeoffs...

First, to get the optics for such a large zoom range small enough to work with a pocket-size camera, the sensor needs to be smaller (larger sensors require larger lenses). So, for example, the excellent Canon PowerShot S120, with 24-120mm zoom, has a 1/1.7-inch sensor, while the equivalent superzoom in the Canon line up, the Canon PowerShot SX280, has a significantly smaller 1/2.3-inch sensor to go with its much larger 20x (25-500mm) zoom range. It has about half the usable sensor area, which means that all other things being equal, it will have as much as twice the noise for any particular ISO. 

Second, the lens on a superzoom often has a smaller maximum aperture. The Canon PowerShot SX280, for example, has a relatively "slow" lens with a maximum aperture varying from f/3.5 to f/6.8. By comparison the  Canon PowerShot S120 has a much wider aperture at its wide end, with a range from f/1.8 to f/5.7. The difference is more light for faster focusing, as well as the potential for higher shutters speeds for capturing action or shooting in low light.

Finally, the combination of a smaller sensor, and trickier optics means that a superzoom will typically produce slightly softer images, with more distortion, than an equivalent camera with a more standard zoom range. So what do you get in exchange for all these sacrifices? ...