I always carry a camera with me when I am out in case I happen upon something interesting. Recently, I have been carrying the Sony DSC-RX100 because it fits easily in a pocket, has a zoom lens, and packs 20mp out of a 1" sensor. The results are really very good. In fact it may be the best pocket camera out there.
The focal length of the zoom lens is equivalent to 28-100mm on a full frame camera. Problem is the word, "equivalent". The real focal length of the lens is 10.4-37.1mm, and even though the maximum aperture ranges from f/1.8-f/4.9, such a short focal length just does not allow for a shallow enough depth of field that would throw a background out of focus -- even when the lens is used wide open.
I happened on the scene below of some stanchions set out on a sidewalk. I wanted to grab a shot that singled out the stanchions and left the distracting background out of focus. As you can see, even wide open the depth of field is to deep.
I was close to home so I went back for my Nikon D800 with a 105mm f/2 lens and a 70-200mm f/2.8. You can see the difference in the two bottom images.
|Taken with the Sony RX100 with the lens racked out all the way to 37.1mm (equivalent to 100mm) and shot wide open at f/4.9. The distracting background is too much in focus -- exactly what you would expect with a 37mm lens.|
|This photo was taken with a real 105mm lens on a Nikon D800. The lens aperture was wide open at f/2. This caused the background to be completely blown out into a nice bokeh.|
|Here a 200mm focal length was used on the Nikon 70-200mm lens at f/2.8. Once again the out-of-focus background and foreground add nice bokeh that enhances rather than detracts from the scene.|