Noise, resolution and sensitivity
Although the sensor in the Fujifilm X-S1 is bigger than a typical compact camera sensor, it is only around 0.7mm wider and 0.6mm taller than the 1/1.6in sensor used in the Panasonic Lumix DMC-LX5. We would therefore expect the X-S1’s performance to be closer to a compact camera than a DSLR, or perhaps even to the Nikon 1 series or a micro four thirds model.
In reality, the X-S1 performs exactly as expected. Luminance noise is well controlled, particularly at low ISO sensitivities, but it begins to creep in by ISO 400. At the maximum ISO 3200 setting, noise reduction has created a slight smudging and loss of detail in JPEG images, although detail is still present in raw images if you are prepared to tolerate the luminance noise.
Chroma noise is far better controlled, and although there is a hint of it at ISO 3200 it isn’t too much of a concern and can be reduced in raw images.
The X-S1 can shoot at ISO 6400 and ISO 12,800, but at a reduced resolution of 6 and 3 million pixels respectively. While shooting at these resolutions reduces the amount of noise, it also reduces the detail present. For the most part I would avoid using either of these ISO sensitivities or resolutions, unless there is no other option or you are only planning to make small images or display them on screen.
In terms of resolution, the X-S1 seems to be let down by its lens. The camera only reaches around 20 on our test chart. As we would usually expect a 12-million -pixel camera to reach 22 or even 24 on the chart, this figure is a little disappointing. This is confirmed by the test charts from the Fujifilm X10, which managed to reach 24.
So although the 24-624mm lens may be very versatile, the extreme zoom does compromise image quality.
Resolution, noise and dynamic range: These images show 72ppi (100% on a computer screen) sections of images of a resolution chart, captured with the lens set to around 50mm. We show the section of the resolution chart where the camera starts to fail to reproduce the lines separately. The higher the number visible in these images, the better the camera’s detail resolution is at the specified sensitivity setting.
