Fujifilm X100s Review

Image Quality

Before we get into the tests we will show a sample image that illustrates the image quality of the X100s. For a scene like the one captured here we rate the image quality excellent. As we shall see later, the quality drops when the light is less than optimal. To do this image justice it pays to download and examine the full-sized JPG from the link below the image.

F11, ISO 200, 1/250 s on tripod - processed from RAW original

Click on image for a larger version

Full-size JPG (9 MB)

Sharpness, Contrast and Diffraction

The test chart was shot at ISO 200. The distance to the target was kept constant between center and corner shots. In the drop down we show 100% crops from RAW originals with unsharp mask 150%, radius 0.9, threshold 0 applied. The center images were focused using autofocus. The corner images were manually focused since the autofocus point cannot be moved into the corners (whereas the manual focusing area can).

Our findings on resolution and contrast are summarized as follows:

The bottom line is that this lens is sharp from F2.8 to F8 with F5.6 best overall, but the differences are small in this range. F2 is absolutely useable, but exhibits low contrast. At F11 diffraction is setting in and F16 suffers significantly from diffraction. F11 in the corner is slightly worse than F16 in the center.

Macro Mode

For the example below we shot of an HO scale locomotive near the closest available focusing distance in macro mode (10 cm (about 4 inches)). Due to the short focal length of the lens (23 mm) the magnification achieved isn't that high and we do not consider this macro function a true substitute for a DSLR with a dedicated macro lens. The height from the rails to the roof of the locomotive is about 5 cm (2 inches).

The scene

Below we show crops of the area marked above. The images were shot in JPG and long exposure time noise reduction was on. Due to what must be a firmware bug, noise reduction kicked in whether or not noise reduction was set to ON or OFF in the menu.

Click a thumbnail to browse a larger version, or click the provided links to download 100% crops:

F16 - 100% crop	F11 - 100% crop
F8 - 100% crop	F5.6 - 100% crop
F4 - 100% crop

The best apertures in macro mode are F8 and F11. By F16 diffraction has set in. F5.6 is acceptable, whereas F4 and below doesn't yield acceptably sharpness.

We also shot the locomotive in RAW. Below is an example at F11, with unsharp mask 150%, radius 0.9 applied in Photoshop CS6. We were able to edge out a bit more sharpness of the camera than the built-in JPG conversion could yield.

F11, developed from RAW - 100% crop

Noise

To test high ISO noise we took some night shots at the same scene we used in our Fujifilm X20 review. The images were shot in JPG since the X100s doesn't allow the full ISO range in RAW (only ISO 200 to 6,400 is available in RAW). Noise reduction was set to its default value.

The images are very clean through ISO 800 (note the details in the chair to the left). ISO 1,600 and 3,200 are very good, with only a slight loss of detail. At ISO 6,400 notable detail is lost (note the gate and the sign to the lower right), whereas noise isn't an issue until we get into the extended range, ISO 12,800 and 25,600. ISO 25,600 loses quite some detail in the shadows, but otherwise does quite well and yields useable images.

ISO 100 is no improvement over ISO 200, we actually found ISO 200 better. We observed this in other scenes as well - we did not find any image quality reason to use ISO 100.

Overall, an excellent low light/high ISO performance.

Vignetting

Vignetting is not an issue with this camera. Wide open the light fall-off in the corners is less than one third of a stop, and at F2.8 it has dropped to one sixth of a stop.

Distortion

The pattern of distortion is interesting. There is some visible barrel distortion at the middle of the top and bottom edge but none at the left and right-hand edges. A circular part of the image with a diameter of the picture height is bulging outwards. The distortion is less than 1% and is not visible in practice unless you're shooting architecture face on.

The distortion is the same in RAW and JPG. Adobe Photoshop does not have a profile for the X100s, but the profile for the X100 in Adobe Camera Raw version 7.4 corrects the distortion somewhat.

Straight out of camera (JPG or RAW)

RAW image corrected in Adobe Camera Raw with the X100 profile

Flare and Aberrations

The X100s is not particularly flare resistant. It exhibits flare and ghosting when a strong light source is near, but outside, the frame. Our night shots, however, came out perfect with no flare but the expected star-shaped pattern from the diaphragm. We recommend purchasing the lens hood for day-time use (it wasn't available to us, so we couldn't test its effectiveness). Click any thumbnail to browse larger versions.

F5	F5.6 (cropped from the left)
F5.6, EV comp +1 (cropped from the left)	F5.6

Chromatic aberration is not an issue with the X100s. We took several backlit shots at various apertures and couldn't provoke any chromatic aberration.

Exposure and White Balance

White balance is accurate except in tungsten light, where the images come out slightly to the warm side (but not more so than it looks pleasing). We left it on auto throughout the tests.

Images shot at ISO 100 tend to be overexposed with clipping occurring in the yellow color.

From ISO 200 and up exposure is generally accurate, but the matrix metering doesn't always do a good job of determining where to meter a scene, and the X100s tend to produce slightly overexposed and flat images in particular when the light is low like in evening light or when the scene is complex to meter:

Flat and overexposed	Improved in Photoshop with Auto Levels
Straight out of camera	Some detail pulled out of the RAW image

To get the best quality form the X100s in scenes like the above one should underexpose a third or two thirds of a stop and post process. Shooting in RAW would give extra leeway for improving the image. RAW file are large, 32 to 33 MB.

Auto flash yields well-exposed images (note that auto flash can only be used in Program exposure mode):

Bokeh

The focal length of the lens is quite short at 23 mm which means that depth of field never gets real narrow. At closer focusing distances, though, separation of the subject from foreground and background can be achieved with the aperture opened up.

The rendering of the out-of-focus areas ("bokeh") is average, neither smooth, nor harsh.

Click any thumbnail to browse larger images.

F2.0	F2.8
F4	F5.6
F8	F11
F16

In our judgment bokeh is only average.

Fujifilm X100s and Pentax K-5 IIs Mini Shootout

Since the X100s as well as the K-5 IIs has no low-pass filter and both have a 16 MP sensor we would expect about the same image quality from the two cameras so we set out to verify that expectation. The K-5 IIs was outfitted with the FA* 24mm F2 lens, the closest we could get to the 23mm F2 lens of the X100s.

The images was shot at F8, ISO 200, extended dynamic range was set to off (since the X100s doesn't have this option at ISO 200) and with autofocus on the Southern Pacific letters. The cameras were mounted on a tripod and released with the 2s self-timer.

The scene - the crops below are "100% crops"

To get comparable exposures we had the X100s on +0.33 EV and the Pentax at +0.5 EV. The brightness value of the letter "P" is identical in the two images. Our findings:

• The K-5 IIs has significantly more dynamic range
• The K-5 IIs exhibits slightly more resolution (notice the back of the chairs)
• Both caneras produce excellent results

In our next example the K-5 IIs shows more texture in the metal parts and again more dynamic range:

The scene, again F8 and ISO 200, no EDR - the crops below are "100% crops"

Perhaps the X100s employs noise reduction already at ISO 200 and that's the cause of the lack of detail?

Image Quality Verdict

The image quality is excellent in sun light and at night, but only good to very good in twilight, where the images tend to be overexposed and flat. It pays off to shoot in RAW in such situations and underexpose a bit. Bokeh is average. Dynamic range as well as resolution is slightly below what a 16 MP CMOS sensor is capable of delivering.

Another thing to watch out for is flare; we recommend getting the optional lens hood. Finally, F16 should be avoided due to diffraction, but that is to be expected for a 23 mm lens in the APS-C format.