The SW20's build quality is reassuringly robust. The brushed silvery and black plastic feels very solid, although the overall weight is about 60g heavier than the SDR-S7. It's about 1cm wider and longer, too, but would still just about fit in a trouser pocket. To maintain its water and dust resistance, the SW20 has much sturdier panels on its ports than a regular camcorder, and each one has a rubber seal.
The catches are also quite hard to open accidentally. Unsurprisingly, the ports hidden therein don't include microphone or headphone jacks - you wouldn't be able to use them underwater anyway. For similar reasons, there is no accessory shoe either. But the lens itself has no cover, instead being protected by a small window of toughened glass. This will need regular cleaning if you really do shoot underwater regularly.
Other than the toughened casing, however, the SW20 has essentially the same specification as the SDR-S7. It's built around a 1/6in CCD sensor with a gross 800,000 pixels, although only 400,000 of these are used for video in 4:3 mode, and only 350,000 in 16:9 mode. Still images can be snapped at 640 x 480, which is surpassed by a lot of camera phones these days - even Apple's iPhone.
The SW20 records standard definition video, but at the slightly non-standard resolution of 704 x 576, rather than the usual 720 x 576. Three levels of compression are available. The top XP mode runs at 10Mbits/sec, whilst the just passable SP mode uses half that. The heavily compressed LP mode consumes 2.5Mbits/sec, but you would only want to use that if image quality is not a major concern and you need to record many hours of footage. Video is stored on an SDHC card, although none is supplied so you will need to factor this into the price. A 16GB card will hold over three hours of footage even in XP mode, so you probably won't feel the need to
