Defined by a combination of focal range, aperture and composition, the "sweet spot" of an image is the area in a photo that’s the most sharp and clear. This sweet spot is used to bring your viewer’s attention to the area of the image on which you’d most like them to focus. For general-purpose photography, sweet spots should be crisp and highly defined, and most lenses are constructed to project an image circle to the sensor that has as little aberration as possible, with edge-to-edge uniformity and a sweet spot that’s surrounded by a soft, pleasing bokeh (the out-of-focus portions of the image).
There are a group of specialty lenses, on the other hand, that are able to provide far more control over the sweet spot of an image. These selective-focus lenses allow you to adjust the plane of the incoming image so that it’s not projected perfectly parallel to the sensor, but rather it’s slightly, or even drastically, distorted. By doing so, specialty selective-focus optics like tilt-shift lenses are able to correct for geometric perspective distortion when up close to larger subjects like buildings, and they can provide creative applications, as well, like miniaturization effects when used at longer distances from subjects.
These types of creative applications are where the Lensbaby line of selective-focus optics comes in. Designed for fun, creative effects like soft focus, artistic distortion, and pinhole and fisheye wide-angle views, Lensbaby selective-focus optics are different from tilt-shift lenses in that they have a curved field of focus rather than the flat adjustments provided by tilt-shift lenses. They aren’t designed to correct perspective, but instead, much like a bellows-style camera, you can position and modify the direction of the focused area in the image. The end result is a moveable sweet spot that’s surrounded by a soft, dreamlike bokeh.
THE OPTIC SWAP SYSTEM
Two new products in the Lensbaby line, the Composer Pro and the Sweet 35 Optic, have updated the series with an optic set that’s still affordable but offers a more professional build than previous models. Compatible with the previous optics and accessories in the Lensbaby system, the Composer Pro builds on its predecessor, the Composer (which is still available), with an improved, more durable metal ball-and-socket configuration. Like a tripod ballhead, the metal ball allows you to aim your sweet-spot focus with smooth and fluid movements. Composition can be locked down with the locking ring on the base; the locking ring also adjusts tension to slow movements or free them up.
The Composer Pro is one of five available Lensbaby SLR lenses. The lenses act as the base for the Lensbaby Optic Swap System, which lets photographers add a variety of Lensbaby optics to the Lensbaby lenses for different looks. There are currently seven swappable optics in the line, including the vintage appeal of the Single Glass Optic, the Plastic Optic for a "toy camera" look and the Fisheye Optic for extreme wide-angle images that are similar to the view provided by a peephole in a door.