In fact, this issue was deemed so important that, in 1992, a group of leading camera and lens makers developed the BTA S-1005 standard for the B4 lens mount which defined the physical, optical, and electrical connections, as well as stipulating that a 2/3 image sensor must have a diagonal size of 11mm. Standardizing the way that lenses mount onto cameras strengthened the marketplace by allowing customers to freely choose whatever lens brands, models, and types best suited their preferences and applications.

Operators often take for granted the contribution their lenses are making to the overall picture quality of their shows and streams. This is because, when lenses perform exceptionally well, its like pure magic. With complex physics at the heart of their design, camera lenses are built with multiple pieces of shaped glass that bend light and then focus these light beams onto the cameras internal image sensors. These glass elements must work together with precision to form a picture thats sharp across the entire image, including the corners and edges.

Its also easy to forget that, in many cases, professional broadcast and digital cinema lenses can cost more than the camera itself. This is especially true for zoom lenses, which must maintain focus while zooming. High-end professional lenses also incorporate optical stabilization, auto focus, and/or servo focus and zoom controls.

While there are many adapters on the market enabling the use of B4 mount lenses on EF- or PL-mount single sensor cameras, there are operational tradeoffs, such as the loss of more than 2.5 F-stops. B4 lens mounts are designed to ensure that the lens mounts flange properly positions the lens relative to the image sensor.

When the lens is mounted onto a B4-compliant camera lens opening, a pin on the top side of the lens flange is inserted into a hole in the camera mount and theres a ring around the outside that when rotated tightly locks the flange of the lens to the camera, further ensuring that the lens isnt mounted at an improper angle.

With the B4 lens mount, the acquired image is projected 48mm beyond the lens mount flange onto the image sensor. A prism then splits the light into separate red, green, blue image planes that form the TV picture. The B4 standard also supports the way electrical signal connections are made to power the lens motors, control the iris, and allow buttons on the lens handle to control camera functions.

When the broadcast industry first migrated from standard definition to high definition, B4 lens mount standardization allowed video professionals to attach their existing SD lenses to new HD cameras. Since the B4 standard defines the diagonal size of the projected image onto the sensorbut not the resolution to be usedthis meant that early HD camera adopters could wait until the time was right to invest in pricier HD lenses.

All broadcast and professional production cameras systems from Hitachi Kokusai use the B4 lens mount with three 2/3 sensors mounted on a prism. This includes the Hitachi Z-HD5000, Z-HD5500, SK-HD1800 HDTV camera systems, as well as the SK-UHD4000 4K camera.

Learn more about Hitachi camera systems, lenses, and other production tips and tools at our website. And be sure to watch a Short Takes video on how to setup camera componentssuch as the lens, viewfinder, SMPTE cable connection, and zoom controlin our online Video Gallery. At Hitachi, we strive to make your live shows and streams go as smoothly as possible, while giving you the flexibility to choose the best lenses for your production needs.