Casio has given its best-selling Exilim Zoom digital still camera an update with the addition of a higher quality image sensor. The camera was announced in Tokyo just a day after Sony launched its DSC-T1 aimed directly at stealing sales from the Exilim range.

The new camera, the Exilim EX-Z4, is the first in the Exilim family to feature a 4Mp class image sensor. It also has a 3x optical zoom lens, like its predecessor the EX-Z3 launched back in April this year.

Other features are largely unchanged from the EX-Z3, but the lack of update is not necessarily a bad thing because Casio appears to be on to a winning format, as since April the EX-Z3 has been the best selling digital camera in Japan, according to figures from GfK Japan.

It's directly in competition with Sony's DSC-T1. Sony's rival offers higher, 5Mp resolution, but for most applications, including printing out images, Casio's 4Mp is more than enough.

The Sony model also has a 3x optical zoom lens and Sony has managed to cram the lens into the body of the camera so it sits sideways and captures images through a prism that redirects light from in front of the camera. Casio's device has a conventional zoom which extends in front of the camera and that means a slightly longer start-up time, as the zoom is extended, and a little more noise.

In terms of size, there is almost nothing between the two cameras. The DSC-T1 measures 87x57x23mm making it slightly narrower and shorter than the Exilim, but also a little thicker.

The Exilim is lighter at 129g, compared to the DSC-T1 at 155g, but users are unlikely to notice a big difference in the weight between the models.

The biggest difference between the two in the eyes of consumers could be price and here Casio has the advantage. The EX-Z4 will go on sale in Japan from 7 November for around ¥50,000 (£270) while the DSC-T1 will be available from 27 November priced ¥60,000 (£323). Casio said the new Exilim has recently gone on sale in some international markets and will go on sale in others soon.

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