Samyang 24 mm F1.4 ED AS UMC is a high quality, fast aperture, prime wide angle lens for Full Frame or APS-C sized sensors for: Canon, Pentax, Samsung NX Sony Alpha (A Mount), & Olympus Four Thirds (NOT Micro four thirds) digital cameras. A Nikon (AE version is available, (listed separately). It is ideal for full-frame cameras, constituting a high-quality wide-angle lens perfect for street, landscape & architecture shooting even in low light conditions. The sharpness is excellent, even at the edges of the frame at wide apertures, & the fast f/1.4 aperture is able to give a narrow depth of field when required. Photographers using Canon DX / APS-C sensors will get approx 38mm field of view (35mm equivalent) suitable for journalist & general photography. On Four Thirds cameras the field of view would be Approx. that of a standard 50mm lens (35mm equivalent), offering a fast aperture standard prime lens. Samyang 24 mm F1.4 ED AS UMC is a manual focus lens. The manual focus ring is wide, easily accessible & perfectly adapted to most photographic applications, except applications such as sports or where Autofocus lenses would be better considered. For film & video applications manual focus is often the preferred choice, allowing changing focusing during filming & here are increasing numbers of users using DSLRs for filming & High Definition (HD) video. This Samyang 24mm f/1.4 ED AS UMC Lens has a standard coupled (clicked) aperture, adjustable in 1 stop (1 EV) intervals. Many of the Samyang lenses (primarily for Canon EOS Mount, although some other mounts also) can also be specially ordered with uncoupled (de-clicked) manual aperture if the primary use of the lens if for video / film making. This allows smooth changing the aperture whilst filming, rather than the clicked 1 EV stop intervals. (AVAILABLE ON SPECIAL ORDER, dependent on mount / availability). Please ask your local Samyang UK retailer for details. For general photography the standard coupled aperture is generally preferred to avoid accidental change of the aperture during photographic sessions or whilst focusing. Accurate focus at very close distance or focus critical situations can be achieved through use of focusing in live view mode, available to most newer camera models. Furthermore the 24mm provides lovely bokeh (the character of out-of-focus areas), due to its design & fast aperture. Optical construction of the Samyang 24mm lens features 13 lenses arranged in 12 groups, 4 lenses are low-dispersion glass (ED), plus two aspheric elements. The 24mm features Ultra Multi Coated (UMC) multi-coated lenses for the best possible light transmission, & resistance to ghosting & flares. The Samyang 24 mm F1.4 ED AS UMC lens offers a professional wide angle prime lens with excellent optics, yet still manages to deliver significant value for your money. Supplied with detachable petal shaped lens hood, lens caps & soft lens bag. Filter size is 77mm.