Tuesday, August 14, 2012
Hi-Tech Studio: Pro Backup Cameras
Think about going mirrorless for your go-anywhere, anytime camera. These compact systems give you high image quality and HD video capability.
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This Article Features Photo Zoom |
 Pentax K-01 |
Due to their short flange-back distances (the distance between the lens mount and the image plane), mirrorless cameras can use pretty much any lens for which an adapter can be found. Adapters are available from a number of manufacturers, including Novoflex and Pro-Optic, to mount a wide range of lenses on most popular mirrorless models. Bear in mind that when you use lenses other than those designed for the mirrorless models, focusing will be manual only, and exposure will be manual or aperture-priority AE. Nikon, Olympus and Sony, however, offer adapters for their DSLR lenses that retain automation, and the Pentax K-01 accepts the full range of Pentax K-mount DSLR lenses, no adapter required. Sony's LA-EA2 adapter not only lets you use Sony A-mount (and legacy Konica Minolta Maxxum) SLR lenses on NEX mirrorless cameras, but it includes a quick continuous phase-detection AF system like the one in Sony's SLT-A65 DSLR.
AF
Most mirrorless interchangeable-lens cameras use contrast-based AF, which reads focus right off the image sensor. This is very accurate, but historically has been slower than the phase-detection systems used in DSLRs and not well suited to action subjects. Newer mirrorless models have greatly sped up contrast AF to where it now rivals phase-detection AF in speed under many conditions. Some mirrorless cameras provide touch-screen focusing; just touch the point in the scene on the LCD monitor where you want the camera to focus.
Nikon's 1 series—the Nikon 1 J1 and V1—features a unique hybrid AF system using both contrast-based AF and phase-detection AF via sensors on the image sensor, and this provides quick and accurate results with a wide range of subjects, including action ones. The Sony LA-EA2 adapter provides the same AF speed and accuracy as the SLT-A65 DSLR because it uses the same phase-detection AF system with the same lenses.
 Nikon 1 V1 |
DSLRs have eye-level optical viewfinders, which are "on" all the time; you can just bring the camera up to your eye to see what the view through the lens looks like, even if the camera is switched off. Mirrorless cameras provide live viewing via the external LCD monitor, and some also offer built-in or optional detachable eye-level electronic viewfinders, but you can't use any of them unless the camera is switched on and "awake." Additionally, the eye-level electronic viewfinders aren't as clear as the SLR finders in pro DSLRs, especially for low-light and action shooting (but they're rapidly getting better; the one in Sony's NEX-7, for example, is excellent). And the external LCD monitor is a good framing device for the types of shooting for which a "carry-all-the-time" camera likely will be used (especially those with touch-screen AF).
Video
All of the mirrorless interchangeable-lens cameras can do high-quality video, either HD (1280x720) or full HD (1920x1080). This makes it easy to capture motion and sound, as well as still images. Actually, since they're in Live View mode all the time, the mirrorless cameras make doing video easier than with a conventional DSLR, as you're already viewing via the LCD monitor or EVF and don't have to transition from using the DSLR's eye-level optical viewfinder to LCD monitor viewing. (As mentioned, Sony's SLT translucent-mirror DSLRs are also in Live View all the time, and provide both eye-level viewing and continuous phase-detection AF for video as well as still shooting.)
Battery Life
Because they're always in Live View mode (and many use smaller batteries to keep camera size down), mirrorless cameras get fewer shots per battery charge than DSLRs. This isn't a major problem as the typical 200-400+ shots per charge is adequate for most "have-it-with-you-always" camera uses, and carrying a spare battery or two is always a good idea regardless of camera type. Just be aware that you won't get as many shots as you're used to with your DSLR.
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