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may see it written as the EOS Rebel T6i/750D.

      ❯❯ Sony dSLRs and SLTs are identified by the letter A, followed by a two- or three-digit model number, such as the A99 or older A300. When you pronounce the name, you can say A as you would any other A, or you can say Alpha. New Sony models are all SLTs, which have translucent mirrors that do not need to move out of the way when you take a picture. The A77 II is a dSLT, although you may see it listed as an Interchangeable Lens Digital Camera (ILDC).

      Sony calls its digital Single Lens Translucent cameras SLTs. They are, in essence, dSLRs with the moving reflex mirror replaced by a translucent mirror that doesn’t move. The more general acronym is dSLT. For more information on how dSLTs differ from dSLRs, jump ahead to the upcoming section, “Mirror and viewfinder type.”

      ❯❯ Pentax dSLRs use the letter K followed by an identifying number, such as the K-70 and K-3 II.

      ❯❯ Olympus has phased out its digital SLRs in favor of the popular OM-D mirrorless “Micro Four Thirds” line (named Micro because they do not have the same mirror and optical viewfinder as standard Four Thirds system cameras). OM-D (I keep wanting to write “OM-G!”) cameras have interchangeable lenses and most of the same features as dSLRs. Although I don’t cover mirrorless cameras in depth in this book, they look, feel, and act like dSLRs in most ways. The main differences that you will notice are that they are smaller and thinner than most dSLRs. Like dSLTs, whose mirrors don’t move, cameras like the OM-D E-M10 do not “clunk” when you take a photo. There is no mirror to move. Older Olympus dSLRs are designated by the letter E followed by a number, such as the E-5.

       Sensor size

      Digital SLR sensors vary in size. Aside from the differences in cost and the technical merits of using a smaller or larger sensor, sensor size has a profound impact on how photos look. In effect, smaller image sensors make it look like you’ve zoomed in compared to a camera with a larger sensor. The amount is expressed as a multiplier, and is called crop factor. I have more information on crop factor in the section “Delving into Camera Specifications,” later in the chapter.

      Here are the most popular sensor sizes and their crop factors:

      ❯❯ Full-frame: dSLRs whose image sensors are the same size as a 35mm frame of film are called full-frame dSLRs. This is the gold standard of professional dSLR quality. The aspect ratio of these sensors, and hence the photos you take with them, is the same as 35mm film: 3:2. Full-frame cameras have a crop factor of 1.0x. Nikon full-frame cameras are labeled FX.

      ❯❯ Cropped-frame: dSLRs whose sensors are smaller than a 35mm frame of film are called cropped-frame, cropped, or cropped-body dSLRs. There are several types of cropped-frame sensors:

      • APS-C: This is the standard sensor size for most consumer and mid-range digital SLRs. It's smaller than a 35mm frame of film, but far larger than a compact digital camera sensor. APS-C sensors have a crop factor that ranges from 1.5x (most APS-C cameras) to 1.6x (Canon). Nikon labels its APS-C cameras DX.

       APS-C stands for Advanced Photo System, Classic. APS was a film format created in the mid-1990s. It had three print formats: C (classic print), H (wide print), and P (panoramic print). You chose the format you wanted using a switch on the camera. When developed, the print would come back cropped according to the setting you used. APS film cartridges were smaller and easier to load into cameras than 35mm film. APS cameras and film were quickly overshadowed by the introduction of affordable digital cameras and are not used anymore. Digital APS-C image sensors match the rough dimensions of APS film when shot in the classic format, hence the – C designation.

      • Four Thirds and Micro Four Thirds: These sensors are much smaller than APS-C sensors and have a 4:3 aspect ratio. Four Thirds/Micro Four Thirds sensors have a crop factor from 1.8x to 2.0x.

      • APS-H: This category is not very prevalent today. It’s a “tweener” size. APS-H sensors are smaller than full-frame but larger than APS-C sensors. They have a crop factor of approximately 1.3x.

Figure 1-2 shows an APS-C cropped-frame Nikon dSLR sitting next to a full-frame Pentax camera. Both mirrors are raised, enabling you to see the relative size of the image sensors inside them. The difference in price? About $1,700, including the lenses.

       FIGURE 1-2: Comparing APS-C to full-frame.

       Pixel count

      You will often see a camera’s pixel count – how many pixels make up each photo – listed as part of the name. Digital camera pixel counts are expressed as megapixels (MP), or millions of pixels. Today, even new consumer-level dSLRs have 18MP or more. More advanced cameras have pixel counts ranging from 24MP to 36MP, topping out at an astounding 50MP, which rivals some medium-format cameras (the ones that cost $15,000 to $45,000).

The total number of megapixels affects your photos’ pixel dimensions and file size, as shown in Figure 1-3. The photo’s type, size, and dimension are just below the Image Quality line in this figure.

       FIGURE 1-3: This camera captures photos up to 24 megapixels in size.

       All other aspects being equal, the camera with more pixels will probably serve you better in the long run. While I hate to buy into the premise that more is always better, having greater resolution means that you can crop your photos and have more left over. Having more pixels can also help you fight the urge to upgrade your camera prematurely. Camera technology doesn’t stand still, and you should enjoy the one you have for as long as you can.

       Lens mount

Lenses attach to the body of the camera using a lens mount. Figure 1-4 shows a close-up of the mount on a Sony dSLR. It’s pretty large, and has to be made of metal to stand up to the stresses of mounting different sized lenses. Here is a quick summary of the lens mounts that the top manufacturers use:

      ❯❯ Nikon uses the F-mount, which is standard on both its cropped (DX format) and full-frame (FX format) dSLRs. Nikon also uses the DX classification to identify lenses that are optimized to work on cropped-frame, DX-format camera bodies. Lenses without the DX identifier are compatible with DX and FX-format camera bodies. As a bonus, Nikon’s FX-format camera bodies can use DX-format lenses in a special “DX crop” mode. This mode uses the area in the center of the image sensor and results in a smaller, cropped photo.

      ❯❯ Canon dSLRs use the EF lens mount on all its cropped and full-frame cameras. Canon uses the EF-S lens designation to identify lenses that are only compatible with cropped-frame Canon cameras. All Canon dSLRs can mount EF lenses. Only cropped-frame dSLRs can mount EF-S lenses.

      ❯❯ Sony uses the Alpha mount or A-mount (refer to Figure 1-4). Of note, DT lenses are compatible with cropped and full-frame bodies, but images are recorded cropped on the latter. Sony E-mount cameras such as the A7R and A6300 have dSLR-sized sensors without the mirror or optical viewfinder. A-mount SLR lenses can attach to E-mount cameras with a special adapter.

      ❯❯ Pentax dSLRs use the K-mount. There are several K-mount sub-types that feature different contacts and autofocus drive capabilities. In addition, adapters are available to mount old screw mount Pentax lenses to K-mount cameras.

      ❯❯ Olympus

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