A short while back, I explained the differences between full frame and crop sensors. I’ve since gotten the question, “Well, which one’s better?” The short answer? Both. And if that didn’t work for you, here’s a slightly better short answer: Depends.
Since neither of those answers is particularly helpful, let’s try this again. Let’s start, in fact, by re-framing the question, and then looking at the pros and cons of each. Which one will work best for you, and why?
DX has a “crop factor,” typically in the neighborhood of 1.5x to 1.6x. Here’s what that means in plain English: first of all, it means that the image you’re taking will be enlarged, similar to the effect of using digital zoom but without the loss in optical or image quality. Second, it means more reach on your long lenses. You bought a 200mm lens? Congratulations. It’s going to work like a 300. If you bought a 300, it’s going to give you the magnification of a 450mm. Great news if you routinely photograph things like birds and wildlife. DX, in other words, is like having a built-in teleconverter, minus the added cost and hassles.
Now the bad news. Shooting architecture? A 24mm f/1.8, which would generally be adequate on a full-frame sensor, is now a 35mm. Wide, in other words, but not that wide. You want a “normal” lens, you can pick up a nifty fifty, only to find out that it’s closer to 75mm (so you might end up going for something in the 28mm-35mm range instead). There are wider lenses for DX (several of which start in the 18mm lens, with other options starting anywhere between 11mm and 17mm), but some of these are terribly expensive, or distort at certain apertures.
I’ve also heard crop sensor shooters complain that they’re losing too much at the long end if they shoot in full frame. Having done both, I’ll concede you have a point there. Full frame cameras generally have a crop option built in, however, so you can always switch to that if you need the additional reach. This wasn’t always a great option since you’d lose several MP in resolution, but one upshot to the new crop of FF cameras having a ridiculous number of pixels is that you can now shoot in crop mode at 10mp or more. That doesn’t sound like much, but consider that several older SLRs only shot 6MP. Those 10MP give you all the image quality of a Nikon D60, itself no slouch. That’s also with a newer processor and larger pixels, so it’s not a bad tradeoff.
How about depth of field? As a rule of thumb, smaller sensors give more depth of field, even with all else being equal. f/2.8 on a point-and-shoot, versus a crop-sensor SLR, versus a full frame SLR, will all give different degrees of DOF, even at the same distance to the subject. For some purposes, that added depth of field is a great thing (landscape or macro photography, for instance), but at other times (say you’re shooting portraits), it becomes more of a challenge to throw your background out of focus, and yet rendering your subject with a reasonable degree of sharpness. Remember, even though your lens might shoot f/1.4 or f/1.8 wide open, lenses are usually going to be sharper once you’ve stopped them down by at least a full stop. On a small sensor, that can end up making a significant difference.
Then there’s ISO. If, like me, you like shooting in low light without flash (or you’re shooting sports, and can use an extra stop or three of shutter speed to freeze action), good performance at higher ISO is extremely helpful. Sensor technology – and the processor technology to which it’s linked – gets better every year. My current compact (a Fuji X10) runs rings around the Kodak that it replaced in terms of IQ and high ISO performance, but it couldn’t hold a candle to my old D7000 or my D600 in either respect at high ISO. And I’ve seen a significant step up in noise control between the crop sensor D7000 and its full-frame counterpart, the D600. High ISO may not be your be-all and end-all (especially if you’re shooting with flash, or a full lighting setup), but on the off chance that it is important to you, sensor size can (and often does) make a difference.
Finally, there’s image quality. There are several variables that influence how your images will look (exposure, sharpness, good lenses, filters of good quality if you’re in the habit of using them, camera settings, et cetera, et cetera). With that said, larger sensors tend to give higher picture quality (partly due to resolution, partly because the photosites (pixels) are larger) than their smaller counterparts. They also tend to give more latitude in terms of dynamic range and rescuing shadows or highlights that are under/overexposed. Take a look at the photos out of a Phase One or Mamiya medium format camera versus your average SLR, and there’s a pretty significant difference there.
These are hardly the only considerations, of course. There’s weight, cost of bodies and lenses, controls, and a lot more. The broader point, then, is if you’re buying your first interchangeable lens system – whether it’s going to be Micro 4/3, Four Thirds, APS-C, Full Frame or something else altogether – you’ve got some serious research and thinking ahead of you. You’ll want to think about your budget, and what you’re comfortable schlepping on a long day’s shooting, to be sure; but don’t forget to give some thought to your subject matter, as well, since that’s going to have a significant impact on the kind of bodies and lenses you’ll want to check out.
Your turn. Have you shot with multiple formats (including those of you who shot with film for years before shooting digital)? Sound off about your experiences!
