SENSOR SIZE

If there’s one rule to follow in photography, it’s that bigger sensors mean better photos. That’s a generalization, of course, but it’s based on a very basic empirical truth: the bigger the photosensitive surface area, the more light is taken in at a time. Practical evidence for this is abundant, from the Nikon 1 series that disappointed everyone with its undersized CX sensor, to the Nokia Lumia 1020, the best cameraphone on the market largely thanks to its enormous 1/1.5-inch sensor.

Full-frame cameras derive their name from the size of their sensors, which match the “full frame” of 35mm film, and are predictably the professional’s favorite option. With a full-frame camera, a 24mm lens gives you exactly that focal length, whereas with smaller sensors, you’re subject to a crop factor that tends to turn everything into a slightly more zoomed-in version of itself (i.e. if the sensor is 1.5 times smaller than full-frame, as with Nikon’s popular DX format, you get 1.5 times the focal length; with a 24mm lens; that’d mean an effective focal length of 36mm).

Alas, price and sensor sizes scale rather proportionally, so medium format and full-frame cameras are usually outside the reach of most enthusiasts, which is why the most popular digital SLRs like the Canon Rebel T4i today feature the APS-C format. It’s a happy compromise.

MEGAPIXELS

Strictly speaking, a megapixel contains 1 million pixels, but it’s somewhat meaningless to know that your camera shoots 10 million pixels at a time. What you want to know, and what the megapixel count truly tells you, is how big you can make your image without having to enlarge it digitally (and suffer the resultant degradation in image quality). A 3-megapixel photo is more than dense enough to be printed out at the US standard 6- by 4-inch size at 300ppi, while 9 megapixels get you closer to a regular sheet of paper at the same density. Compromise a little on the pixel density, say down to 200ppi, and you’ll get massive printouts from a humble old 12-megapixel shooter. Now, there are no guarantees that the actual photo would look good — megapixel numbers only measure the number of data points recorded by the camera — but at least you’ll be able to do it.

Practically speaking, however, you’re not likely to need such huge images. Most digital imaging ends up being consumed on computer screens, and if all you need are new profile shots for Facebook even a solitary megapixel will suffice. If you’re shooting for billboards, murals, or other enormous photo sizes, you should get all the megapixels you can (like the whopping 36 from the Nikon D800) but for the average photographer, other specs matter far more.

VIEWFINDER / LCD

Optical viewfinders are a funny thing. Until you use one, you wonder why everyone bothers with the effort, then you get your first DSLR and suddenly you can’t live without one. Mirrors in SLR cameras reflect the exact image that will be imprinted onto the sensor through a sort of porthole atop the camera: that’s your viewfinder. Once again, the more expensive models offer a more luxurious experience, with the Canon 7D and Nikon D700 featuring bigger, more comfortable viewfinders than entry-level DSLRs. Electronic viewfinders (EVF) are getting much better and starting to compete, particularly in Sony’s line of single-lens translucent (SLT) cameras like the A77, and they offer helpful guides and more information to make your shot better anyway. It’s features vs. accuracy, and while the purists tend to stick with optical viewfinders, the electronic variety is catching up quickly.

If your camera doesn’t have a viewfinder, then you’d better make damn sure it’s equipped with a good LCD. You’ll be using it to both frame and review photos, so any shortcomings in terms of color fidelity or resolution can force you into a guessing game you don’t want to play. LCD resolution is measured in dots, with 230,000, 460,000, and 920,000 being the typical values. The more dots the better, obviously, but do take a moment to check out the quality of the screen as well. Sony and Samsung are using OLED displays in some of their latest cameras, which look fantastic. Touchscreens are finally starting to get good, too, from the tap-to-focus features on the Olympus PEN E-P5 to the completely touch-friendly Canon T4i — they’re not essential yet, but are increasingly a great thing to have.