Full-frame DSLRs are hot! The reasons? Well, image quality, for starters: All other things being equal, a full-frame sensor can collect more light than a smaller one, and that means a better signal-to-noise ratio (see the sidebar for more about this). And that means better image quality, with less noise, especially at higher ISO settings—full-frame DSLRs hold the top 17 positions in DxOMark.com’s RAW sensor ratings for high-ISO performance, while the highest-rated APS-C camera ranks twenty-first. Full-frame sensors also have room for more pixels of a given size, and more pixels mean more detail can be recorded.
Another potential advantage is that full-frame sensors also "see" more of the image produced by any given lens, while smaller sensors "crop in" on that image, producing a narrower angle of view. For example, a 16mm lens on a full-frame camera shows the same angle of view it does on a 35mm film SLR, but frames like a 24mm when used on an APS-C DSLR. This makes serious wide-angle photography easier with a full-frame camera. There are a number of excellent 16mm prime lenses and 16-35mm zooms available; to get that wide an angle of view with an APS-C DSLR, you’d need a 10.5mm lens, of which there aren’t as many choices.
Of course, the above benefits have been there from the first full-frame DSLR. (Canon’s original EOS-1Ds, in 2002, was the first really successful full-frame DSLR.) What has changed recently is the introduction of full-frame DSLRs at a much more affordable price point: Canon and Nikon offer new full-frame models—the EOS 6D and Nikon D600—that list for $2,099. The price of Canon’s EOS 5D Mark II has dropped to $2,199 now that the EOS 5D Mark III has joined the line. And Sony has produced the first full-frame translucent mirror SLT (more on that technology later) at a list price of $2,799.
That’s still higher than APS-C DSLRs, but roughly half the price of the top-tier pro cameras. Why do those pro models cost so much more? Mainly because they’re more ruggedly built, can shoot 10 or more frames per second, and have better autofocus (AF) and metering systems and higher usable ISO capabilties. But the new "entry-level" full-frame models are no slouches: The Nikon D600 rates third overall in DxOMark.com’s sensor ratings.
These new lower-cost models aren’t the first such cameras—Sony introduced the now-discontinued full-frame DSLR-A850 at $1,999 in 2009. But this is the first time there have been so many options. If you like Canon, there’s the full-frame EOS 6D for $2,099 (also, the EOS 5D Mark II at $2,199, the EOS 5D Mark III at $3,499 and the flagship EOS-1D X at $6,799). If you prefer Nikon, there’s the full-frame D600 for $2,099 (also, the D800 for $2,999, the D800E for $3,299, the D4 for $5,999 and the D3X for $7,999). And Sony offers the unique SLT-A99 for $2,799, which accepts Sony A-mount and legacy Konica Minolta Maxxum lenses. That’s 10 full-frame DSLRs, half of which list for under $3,000.
Of course, even $2,099 is a lot of money, which is the major "con" to the full-frame DSLR. Full-frame cameras also are bulkier than smaller-sensor models. (I personally like a bigger DSLR body, but many think smaller is better, hence the rapid rise of the mirrorless interchangeable-lens cameras over the last few years.) If you’re a wildlife photographer, a smaller-sensor camera gives you more telephoto "reach:" On an APS-C camera, a 300mm lens frames like a 450mm.