Resolution

The word resolution refers to the number of different image sensing components present on the 'digital film' or sensor inside the camera. It's the same as the resolution of your computer screen - measured in number of pixels (e.g. 3 million) or in pixel dimensions (1024x768). Essentially, the more pixels, the more information is recorded by the camera.

For digital video cameras, the moving video recorded is always at the same standard resolution, equivalent to about 800k (0.8 million) pixels. Many video cameras also have a digital still picture mode, and it is this which is recorded at the higher resolution. So, if you want to use your DV camera as a digital stills camera, the multimillion pixel figure is a key feature to look for.

Zoom - Digital and Optical

Zoom refers to changing the focal length of the lens on the camera - zooming out will give you a 'wide' view, perhaps showing a view of a landscape or the whole pitch at a footbal match, while zooming in homes in on a detail or magnifies a distant figure such as a single footballer.

When you zoom in, you magnify the picture to include only the subject you are interested in. The amount of zoom dictates the magnifying power of the camera lens, so it is an important figure to look out for.

There are two methods of zooming - optical and digital. Optical zoom uses a complex of lens elements to magnify the light in a similar way to a telescope or binocular lens. A very good optical zoom will give you 20x or 22x zoom.

Digital zoom takes a part of the image from the lens and 'blows it up' digitally, creating a larger picture from the digital image. If you've ever seen the same feature on a DVD player, you'll notice that beyond a certain zoom level, you don't see any more picture information - there just aren't enough 'dots' to allow you to zoom forever. Some DV cameras offer a digital zoom of 300x or more, but at some cost in quality. Be sure to have a good look at the image you get at these levels of magnification before taking them at face value.

Image Stabilisers

When you hand-hold a video camera, you may find you never achieve the kind of steady shots you see in football coverage on TV. One of the reasons is that the TV cameras are mounted on big stands to hold them steady. The smaller shoulder-mounted cameras are fitted with image stabilisers which counteract the inevitable tiny movements of the camera to keep the image still.

If you ever want to shoot outdoor or sports video, an image stabiliser will hugely improve the appearance of your shots. Even indoors, you achieve a much more professional effect if you have a good stabiliser on your camera.

Again, there are two types of image stabiliser - optical and digital. The optical stabiliser found in more high-end cameras is produced by a tiny gyroscopic component inside the lens which 'wobbles' to compensate for your camera shake, matching every tiny movement to place a steady image on the sensor. Canon's version is denoted by the Optical Image Stabiliser logo, while Sony have a similar technology called Super Steady Shot.

Digital image stabilisers take the shaky image from the lens and calculate how to return it to a steady recorded image. Because the received image is already damaged by shake, there's a limit to the quality you can get compared with the optical stabilisers. Digital stabilisers are indicated by the presence of Image Stabilisers (Canon) and Steady Shot (Sony) on the camera.

Memory Card/Storage

Your digital video camera is likely to do more than record video - very often it has a digital stills function which means your camera doubles as a digital camera. On some cameras, the still image is just recorded onto the tape as a static image, but with high-resolution still cameras (the ones with something like '1.5 million pixels' on them) the tape will not store the high-quality still picture, so you need a separate storage system for your still shots.

Very often, this storage is provided by some kind of solid state memory card or stick with a certain capacity for storing image data. This will be measured in Megabytes (Mb) which gives an indication of the amount of data in the card or stick. The picture data is usually compressed to save space and allow more pictures per card, so it's difficult to judge how many pictures you can fit.

Remember, the higher your resolution, the bigger each image will be, and the fewer you can fit on the card. If you want to take a lot of high-quality still pictures, get a big card or stick with 64Mb or 128Mb capacity.

The other thing to bear in mind with memory cards and sticks is the format - you might need to purchase an accessory to get the images into your PC or Mac before you can edit and print your photos. Some cameras have a built-in interface for the computer, so look out for this.