OP Home > Gear > Cameras > DSLR Performance In A Point-And-Shoot Size?


Tuesday, July 6, 2010

DSLR Performance In A Point-And-Shoot Size?

The new class of cameras—mirrorless, interchangeable-lens models—gives serious nature photographers some interesting options

Labels: CamerasD-SLRs

This Article Features Photo Zoom

Sensor Size
Mirrorless, interchangeable-lens cameras have DSLR-sized image sensors. Those from Olympus and Panasonic have 17.3x13.0mm Four Thirds System sensors, while those from Samsung and Sony have 23.4x15.6mm APS-C sensors, the size used in many popular entry- and mid-level DSLRs. By comparison, typical higher-end compact digital cameras have sensors one-fifth to one-eighth that size.

The significance of these numbers is this: Smaller sensors can make for smaller cameras (although Sony’s APS-C-format NEX-3 and NEX-5 are currently the smallest mirrorless models). But bigger sensors have more room for more pixels of a given size, or larger pixels for a given pixel count. And all things considered, more pixels, and larger pixels, are better. More pixels mean the ability to make bigger prints before the eye can make out the pixels, as well as the ability to picture finer detail. Larger pixels mean more light-gathering efficiency, which translates to better low-light and high-ISO performance. The mirrorless, interchangeable-lens cameras produce far better image quality than the compact digital cameras, especially at higher ISO settings: true DSLR image quality.

Another important facet of sensor size is its effect on a lens’ field of view. Smaller sensors crop into the image produced by any given lens, creating a “telephoto” effect. Camera manufacturers list a focal-length factor for their digital cameras based on the sensor’s field of view vs. a “full-frame” 35mm image frame’s field of view. A full-frame DSLR frames just like a 35mm SLR; the focal-length factor for full-frame sensors is 1.0x. An APS-C sensor crops in on the image formed by the lens such that it covers the field of view of a lens 1.5x longer on a 35mm camera; hence, its 1.5x factor (Canon’s slightly smaller APS-C sensors have a 1.6x factor, Sigma’s, a 1.7x factor). The even smaller Four Thirds sensor has a 2x factor: A 100mm lens on a Four Thirds (or Micro Four Thirds) System camera frames like a 200mm lens on a 35mm camera.

This is great for sports and wildlife photographers, who seldom can get close enough to subjects for dramatic frame-filling shots: All your lenses are, in effect, 1.5x, 1.6x, 1.7x or 2x “longer.” It’s not so good for wide-angle landscape photographers, whose wide-angle lenses also become “longer” and less wide-angle: A 24mm lens on an APS-C camera frames more like a 40mm lens on a 35mm camera; a 24mm lens on a Four Thirds (or Micro Four Thirds) System camera frames like a 48mm lens on a 35mm camera.

Mirrorless Camera Sensor Sizes

(Micro Four Thirds vs. Four Thirds vs. APS-C)

You can see the relative sizes of APS-C and Four Thirds/Micro Four Thirds image sensors. These are the image sensors that dominate the mirrorless category. To date, there are no mirrorless cameras with “full-frame” image sensors.
When you first hear the term “Micro Four Thirds System,” you may think the sensor is smaller than the sensor used in regular Four Thirds System cameras. Actually, it’s exactly the same size: 17.3x13.0mm. The “Micro” comes from the camera size, not the sensor: Micro Four Thirds System cameras are smaller than Four Thirds System DSLRs, largely because the former lacks the latter’s bulky mirror boxes, focusing screens and pentaprism or pentamirror viewfinders. Doing away with the mirror box means the distance between the lens mount and the image sensor can be decreased and, in fact, that distance in Micro Four Thirds System cameras is half that in regular Four Thirds System cameras, making for much slimmer bodies. Reducing this “flange back” distance also allows the lens-mount diameter to be shrunk some 6mm, which also makes for smaller camera bodies—and lenses.

In theory, the smaller sensors in the Micro Four Thirds cameras should allow for smaller cameras, but not quite as good image quality, while the larger APS-C sensors in the Samsung and Sony mirrorless cameras should produce better image quality, but slightly bigger cameras. In practice, the Four Thirds cameras produce excellent image quality (and the APS-C-format Sony NEX-5 we’re testing is at least as good, so far), and the Sony APS-C models are the smallest mirrorless, interchangeable-lens cameras out there as of this writing. Your decision should be based on how comfortable a given camera is for you to operate and how its feature set and lens selection mesh with your shooting needs, rather than on whether it’s a Micro Four Thirds model or an APS-C model.


Add Comment


Popular OP Articles