While it looks very similar to the EOS 40D on the out side, on the inside it has many improvements to both hardware and operating features. The major change is of course the sensor. The 50D has a newly-developed 15.1-megapixel APS-C CMOS sensor that has larger photocells and larger microlenses that are closer together, increasing the sensor’s light-gathering capability. This is supposed to produce greater dynamic range and less noise at high ISO settings, and we’ll be taking a look at the results shortly.
Incorporated into the sensor module is a self-cleaning system, which activates whenever the camera is switched on or off. It uses ultrasonic vibrations and an anti-static non-stick fluorine coating to remove dust from the sensor. If any particles remain, their effects can be automatically removed using dust delete data from the camera in the included software. Some cameras can do this internally, and nearly all digital SLRs have similar dust removal systems.
The new sensor is coupled with Canon’s latest DIGIC 4 processor, which features 14-bit image processing, producing greater colour depth and smoother tonal variations. The increased speed of the processor gives a big improvement in overall performance, with a virtually instant start-up and very quick image review.
Software-based improvements include a new Peripheral Illumination Correction function, which can automatically compensate for the slight vignetting effect when using some lenses, especially older wide-angle types. The system includes a database of Canon lenses, and automatically detects which one you have fitted.
The 50D has a new image quality option, a third smaller 3.8-megapixel Raw mode setting, along with the 15.1MP and 7.1MP settings. This is presumably to save space on the memory card, since the smaller setting produces CR2 Raw files that are approximately 7.5MB in size, against the 20MB of the full 15.1MP files, or the 12MB of the 71.MP setting. I’m sure someone will find this amazingly useful, but personally I can’t imagine someone willing to spend over £1,000 on a camera who would baulk at paying a bit more for a few large-capacity CF cards.