The Fuji X-A1 is the fourth model in the company's X-series of compact system cameras, but it is identical to the Fuji X-M1 in all but one vital way - the sensor. Whereas the Fuji X-M1 has the same APS-C format X-Trans CMOS sensor as the Fuji X-Pro 1 and Fuji X-E1, the X-A1 has an APS-C format CMOS sensor with a Bayer pattern primary colour filter.While the X-Trans sensor's random colour filter arrangements means it doesn't require an optical low pass filter, the more standard Bayer pattern filter over X-A1's sensor does. This is likely to mean that the 16.3 million pixel sensor of the X-A1 isn't able to resolve quite as much sharp detail as the 16.3 million pixel sensor in Fuji's other cameras. However, we've been happy with Bayer patterns in digital cameras for years, so it may not be a major issue.The change to a more common sensor design enables Fuji to offer X-A1 at a more affordable price than the X-M1; with the X-A1 retailing for around US$599/£499 with the 16-50mm f/3.5-5.6 kit lens and the X-M1 retailing for around US$799/£679 with the same optic.