From the Manufacturer:
The first Sony G Lens created specifically for E-mount cameras is true to its heritage, achieving outstanding resolution and contrast throughout the zoom range thanks to an advanced optical design that incorporates two ED glass elements and three aspherical elements. Thanks to technology originally developed for the Sony Handycam camcorders, zoom and focus operation are not only remarkably smooth and quiet, but the length of the lens remains constant as well, for consistent, stable handling when shooting stills or movies. A zoom lever allows zoom speed to be freely adjusted as required while maintaining a comfortable, firm grip, contributing to maximum image quality with minimum camera shake.
High overall performance and contrast in first E-mount G Lens
True to its high-end G Lens heritage, the SELP18105G lens features two ED glass elements and three aspherical elements for high resolution and contrast throughout the entire zoom range. Distortion at the wide end of the zoom range, and spherical/color aberration at the telephoto end, are effectively controlled so that beautiful rendering with excellent contrast is achieved at any focal length. A circular aperture design ensures that defocused areas are attractive too, providing an extensive palette of expressive imaging options.
Constant F4 maximum aperture throughout the zoom range enhances shooting convenience
A constant maximum aperture of F4 throughout the zoom range provides plenty of "brightness" for fast shutter speeds even in relatively low-light situations. The same shutter speed and ISO settings can be maintained at all focal lengths when shooting stills, and consistently low noise can be maintained throughout the zoom range when shooting movies.
Zoom level for continuous zoom speed control and new expressive freedom
Similar to Handycam camcorders, a zoom lever on the side of the lens allows both variable and fixed-speed power zooming. Variable speed control is step less, for enhanced speed control freedom. The zoom level can be operated while maintaining a stable grip on the camera, minimizing the likelihood that blur will occur due to camera shake. And since an independent focus ring is provided, the zoom ring can be used for power zoom control even while focusing manually.
Handycam camcorder technology for fast, quiet focus
Zoom operation noise has been reduced to the same level as Handycam camcorders. This is the world's first mid-range zoom for APS-C cameras to feature this type of "floating axis" construction used in Handycam camcorders, achieving exceptionally smooth, quiet focus and zoom operation. Another benefit of this type of constructions is that the length of the lens does not change while focusing or zooming, contributing to consistently easy handling.
Optical SteadyShot image stabilization
Built-in Optical SteadyShot image stabilization can significantly reduce image blur. In addition to its advantages for normal shooting, Optical SteadyShot works with the Anti Motion Blur and Handheld Twilight modes to create clear, blur-free, low-noise images at night, indoors, or in any conditions that would otherwise be a challenge due to low light conditions, without making it necessary to boost sensitivity.