A small sensor like the one in the X10 provides a large depth of field. That can be an advantage in many situations except if you want to isolate your subject against a soft background. On cameras with a larger sensor, like an APS-C sized sensor, you control depth of field with the aperture. The larger the aperture (smaller number) you select, the less depth of field you get. On a small-sensor camera the aperture has a much smaller effect on depth of field.
To compensate for that, the X10 provides a shooting mode called Pro Focus which creates blur surrounding the main subject through in-camera processing. When we reviewed the Pentax Q we found a similar mode which Pentax called "blur control". It was hit-and-miss on the Q, so let's if it's any better on the X10.
As mentioned above the aperture is often used to control the depth of field of an image. However, due to the small size of the sensor in the X10, a shallow depth of field cannot be achieved just by opening the lens up. The X10 did slightly better than the Pentax Q in that at F4 we do see the background starting to become blurred, but compared to the K-7 with the APS-C sensor the effect is marginal. It would of course be more pronounced at F2.8 or larger, but apertures larger than F4 might not be usable without overexposing the image due. This is because of the limitations of the shutter of the X10 that we mentioned earlier. At large apertures the fast shutter speeds are simply unavailable! In this scene the shutter topped out at 1/1250s and we needed 1/2500s in order to shoot at F2.8.
We find it this coupling between available shutter speeds and apertures borderline unacceptable. It simply prevents you from using the full ranges of apertures in bright light unless you go to the trouble of mounting an ND filter on the lens (in order to fit a filter you'd have to purchase an adapter).
But now things get even worse. When we had shot our scene with the available f-stops 4 through 11 and wanted to use Pro Focus (blur control) we got the laconic message "Cannot create effect".
This first scene illustrates depth of field and bokeh as created with the aperture.
Thus, we can conclude that if you want to isolate the main subject by controlling depth of field, the Fujifim X10 is not the right choice. A camera with a larger sensor is required so that you can use lenses with a much longer focal length. Fuji has included the "Pro Focus" shooting mode to compensate but as mentioned earlier, that mode was unavailable on the scene above. We had more luck when we moved in on the main subject as we shall see next.
Pro Focus blur control is available as one of the options under the Adv setting on the mode dial. First you set the mode dial to Adv, and then enter the menu and select Pro Focus. The setting is retained so that next time you set the mode dial to Adv the camera will be in Pro Focus mode. The maximum resolution is reduced to 6 MP (2816 x 2112 pixels) in Pro Focus mode and RAW shooting is not available. This mode otherwise works like programmed auto exposure where you have no control over the aperture or shutter speed.
As this test shows, Pro Focus did a very good job ot applying blur only the background. It didn't blur the foreground, though (the plant to the left), which is evidently is closer to the camera than the main subject as can be seen in the K-7 image.
There are no settings to control the strength of the blur, which looks more like motion blur than the optical depth of field blur. However, if only it would work on all scenes, Pro Focus could be a solution in a crunch. It is a drawback, though, that resolution drops from 12MP to 6MP in this mode.