Here’s a gadget I came across at Mobile World Congress earlier this year. The Olloclip is a clip-on supplementary lens for the iPhone or iPod Touch, giving it three new modes: wide-angle, Fisheye, and Macro.

In the box you get the reversible lens with covers for each end, an adapter clip for the slimmer iPod Touch, and a handy bag.

The lens clips onto the corner of the iPhone, covering the on/off button. There are different models for the iPhone 4/4S and iPhone 5, which is a drawback. Every time you upgrade to a new iPhone, you will have to buy a new Olloclip, or do without it. You also lose use on the on/off button when the Olloclip is attached.

Still, that is a small price to pay if you get amazing new photographic capabilities, and to some extent you do. I was particularly impressed by the macro mode. Here is my snap of a coin getting as close as I could quickly manage with the iPhone 4 alone:

Snap on the Olloclip, and I can capture a world of detail that was previously unavailable.

I also tried the wide-angle and fisheye modes, both of which work as advertised.

The twist here is that the Olloclip gives your iPhone camera features which your purpose-built compact camera may not have. If you want or need to take the kind of shots which the Olloclip enables, it is a great choice, spoilt a little by the inconvenience of clipping and unclipping the lens.