One factor that affects depth of field is the sensor size. Simply put: the smaller the sensor, the more extended your depth of field in any given image.
This is an approximation and simplification (it also depends on angle of view, point of view, etc) but it is good for us as photographers.
Clearly, this means that if we want blurry backgrounds, we want large sensors. So what are the choices?
- Lower-end (and many higher-end!) point-and-shoot cameras usually have very small sensors. These do not make it easy to get blurry backgrounds!
- Then there are “almost-APS-C” sensors such as the “Micro four thirds” format – these are almost as big as a crop camera’s sensor. Micro four third cameras are twice as small as a negative. This is the trend in small cameras.
- The next step up is the APS-C crop sensor – 1.6 times smaller than a negative for Canon; 1.5 times for a Nikon. Most DSLRs have this size sensor. Some small cameras now also do (like my Fuji X100).
- Next, there is a Canon-only size that is 1.3 smaller than a negative – this is the 1D’s format.
- And finally, there is the full-frame sensor – it is exactly the size of a 35mm negative.
The bigger the better – also because a larger sensor gives you lower noice and hence higher ISO capability, and a larger, brighter viewfinder.
And this is why we are seeing today’s wonderful move to larger sensors. So my advice: when buying your new camera, do ask how large the sensor is, and go for the largest one you can afford.