Sony Alpha SLT-A33L review

Another problem was that the viewfinder and the main screen – a superb 3in, 921,000-pixel articulated LCD – show the same image, and that image isn’t always what we wanted to see. Image review is off by default, so the camera is ready for the next shot, but we often missed having this function. However, activating it slowed the camera down and got in the way of composing the next shot. Without image review, we measured a shot-to-shot time of 0.5 seconds. With it enabled, it was 1.3 seconds, and longer if we wanted to see the live view image to compose the shot.

Although other hybrid cameras use contrast-detect autofocus derived from compact cameras, the A33 uses the faster phase-detection system found on SLRs. This is possible thanks to a translucent mirror, which reflects some light to the 15-point autofocus system but lets most of it pass through to the sensor. This means that the sensor and autofocus are both permanently active rather than working on a timeshare basis via a flip-up mirror mechanism.

This has useful ramifications for continuous shooting. The Hi and Lo continuous drive modes deliver 6fps and 2.5fps respectively, while an option on the mode dial uses fast shutter speeds to deliver 7fps shooting. That’s impressive at this price, but even more remarkable is that the camera continues to focus during continuous capture – perfect for action photography. It doesn’t keep this performance up for long, though. Testing with a Sandisk Extreme III SDHC card, the buffer became full after 13 frames, whereupon it slowed to 1.6fps. Shooting in raw mode, it fell to 1fps after seven frames.

The translucent mirror also means that phase-detection autofocus is available during video capture. This delivered the quickest, most accurate video autofocus we’ve seen from a large-sensor camera. Various SLRs can record video but, for most, focus is fixed for the duration of clips. The A33 had no such problems, with quick, accurate autofocus while recording – it wasn’t infallible but it’s the best we’ve seen from a large-sensor camera. The only snag is that Alpha lens motors aren’t designed for silent operation, so creaks and whirrs crept into the soundtrack. The microphone was thin and boxy-sounding, too, but fortunately there’s a mic input to solve both problems. Using a cheap Audio-Technica ATR35s lavalier mic improved quality considerably.

Otherwise, the video mode was impressive, recording 1080p at 25fps in AVCHD format. The footage is encoded as interlaced but the source is progressive, giving it a cinematic appearance. Automatic exposures were balanced and details were excellent. Shadows were noisy in low light, though – not disastrously so, but it was disappointing considering the size of this camera’s sensor compared to those used in consumer video cameras.