I think there is some confusion out there about the pros and cons of selecting a DSLR on the basis of a full-frame or cropped sensor. Cameras that are referred to as “full frame” are typically cameras that mirror the 24x36mm size of a traditional 35mm film camera. Cropped sensor cameras come in many sizes and flavors, but usually the APS-C standard is most prevalent. This means you must use a multiplication factor to determine what’s known as an Effective Focal Length (EFL) for your particular camera/lens combo.
There are trade-offs to both systems. Full frame sensors are usually larger, resulting in larger sensor size. This means the sensor sites on the sensor can be larger, which means the images will typically be less noisy when compared with crop-sensor images which must cram more megapixels onto a smaller sensor.
The larger the sensor, the shallower the depth of field for a given subject size. Small P&S cameras have large Depth of Field (DOF.) With a crop sensor, you have larger DOF. This means it’s harder to get a good bokeh and harder to control the backgrounds.
Smaller sensors utilize the central portion of the image circle, which is often sharper than the periphery. This allows cheaper glass to give the appearance of sharpness that’s only attainable on full frame sensors with high-end glass.
A larger sensor usually has less noise than a smaller one, but they require expensive glass to avoid light fall-off at the edges and other optical abnormalities. Note the cheaper glass used in “DX” lenses doesn’t show these optical problems because the circle of confusion is smaller.
Cropped sensor cameras tend to cost less than full frame cameras as do the lenses designed to be used on them. Cropped sensor cameras are typically smaller and lighter because DX lenses are typically smaller and lighter. If you need stealth or lightweight then crop sensors are a better choice.
Obviously, this post isn’t intended to be a white paper on the subject. Rather, some information for those who want to have an intelligent dialogue about the subject without all the emotion that tends to surround this subject.