Monday, November 12, 2012

When a small sensor isn't big enough

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.

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