Tuesday, December 13, 2011
All About Lens Adapters
What to know when you use these devices to expand your optical options
|This Article Features Photo Zoom|
DSLRs and mirrorless cameras provide full automation when you use lenses designed for them. You get autofocusing and open-aperture, through-the-lens metering. Be aware that some adapters interfere with these functions. And, of course, if you're attaching a manual-focus lens such as a Leica or Zeiss, you won't get autofocusing.
The focusing screens in DSLRs weren't designed for manual focusing and lack the focusing aids found in manual-focus SLRs (central split-image and microprism collars on ground-glass focusing screens, for example). Some higher-end DSLRs accept interchangeable focusing screens; if you intend to use manual-focusing lenses with one of these, it's a good idea to buy and install a screen that was designed for manual focusing.
With live-view cameras (many DSLRs and all mirrorless, interchangeable-lens models), you can zoom the live image and focus right on the LCD monitor. A magnifying loupe (and a tripod) can be very helpful here.
Some adapters come with chips that activate an AF DSLR's focus-assist system, so the "in-focus" lamp in the viewfinder will glow when you've achieved focus manually.
Olympus Digital Four Thirds Adapter MMF-2
Panasonic Lumix R Mount Adapter
Flashpoint Tilt Adapter
|Lensbaby Tilt Transformer||
Sony LA-EA1 Adapter
When you use a DSLR with a lens designed for it, you get open-aperture metering. This means that, regardless of the aperture you select for a shot, the lens remains wide open until the instant of exposure, when it stops down to the selected setting. This provides the brightest image for composing and focusing. Most lens adapters break the linkage between camera body and lens that does this, so you'll have to open the lens to its widest aperture to compose and focus, then manually stop the lens down to the desired shooting aperture before making the shot. This can be a problem with action subjects and with lenses that change focus when stopped down. And, of course, it can't be done with lenses that don't have aperture rings, like Canon's EF and Nikon's G series.
Canon EOS DSLRs and EF lenses have all-electronic lens mounts, where all communication between camera and lens is electronic; there's no mechanical linkage aside from the bayonet mount that holds the lens on the camera. Thus, you can't adjust the aperture when using an EF lens on a non-EOS body. However, Redrock Micro offers the LiveLens MFT Active Lens Mount, which lets you attach EF lenses to Micro Four Thirds System cameras and incorporates a battery-powered onboard electronic system that allows you to adjust apertures of EF lenses in 1⁄3- or 1⁄5-stop increments (but you must do this via the Redrock unit, not via the camera body).
Some adapters from Novoflex incorporate an aperture-control ring so you can adjust apertures with lenses that lack one, such as Nikon's G-series.
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