A lens board or lensboard is a photographic part used for securing a lens to the front standard of a

large format Large format refers to any imaging format of or larger. Large format is larger than "medium format", the or size of Hasselblad, Mamiya, Rollei, Kowa, and Pentax cameras (using 120- and 220-roll film), and much larger than the frame ...

view camera A view camera is a large-format camera in which the lens forms an inverted image on a ground-glass screen directly at the film plane. The image is viewed and then the glass screen is replaced with the film, and thus the film is exposed to exactly ...

. The lens board itself is usually flat, square, and made of metal (most commonly

aluminum Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. It ha ...

), wood, or plastic. The lens board will have a hole of various diameters drilled dead center on the board. A lens board typically varies between 1 and 4 millimeters in thickness. The overall size and shape of the lens board depends on the brand of camera and film format used. Some cameras will use 2 to 4 screws to secure the lens board to the front standard of the view camera, most commonly however, the lens board will be secured by one or more locking levers or tabs to allow tool-less removal of the lens board. The rear surface of a lens board is usually painted matte black to keep light entering the camera through the lens during exposure from reflecting off the surface and interfering with the projected image. While most lens boards are flat, some are recessed to accommodate wider focal length lenses which must be positioned closer to the

film plane A film plane is the surface of an image recording device such as a camera, upon which the lens creates the focused image. In cameras from different manufacturers, the film plane varies in distance from the lens. Thus each lens used has to be chos ...

. A recessed lens board effectively reduces the flange focal distance of a camera.

Sizes

Depending on the size and focal length of a particular lens, a certain diameter of hole must be drilled in the center of the lens board to accommodate the shutter assembly . Lens boards are typically available pre-drilled by the camera manufacturer, however, if no replacement lens board is available from a camera manufacturer, then one must be custom fabricated by a machinist. Nearly all large format leaf shutters made since the 1990s are manufactured by the

Nidec Copal Corporation The , or Copal, is a Japanese manufacturer of optical, electronic and mechanical equipment, primarily for the photographic industry. It has been a subsidiary of Nidec Corporation since 1998, and was formerly known as the Copal Corporation. The ...

, therefore the diameter of hole drilled is commonly referred to as the ‘Copal Number’. The Copal sizes are as follows: *Copal #0 - 34.6 mm *Copal #1 - 41.6 mm *Copal #3 – 65 mm *Copal #3s - 64.5 mm The origin Compur/Compound sizes are as follows: *Compur #00 - 26.3 mm *Compur #0 - 34.6 mm *Compur #1 - 41.6 mm *Compur #2 - 52.5 mm (there were different versions like Compur II and Compur II 5/2) *Compur #3 - 65.0 mm *Compound Dagor - 38.0 mm *Compound #3 Hülse 7 - 63.2 mm *Compound #4 Hülse 9 - 69.1 mm *Compound #4 Hülse 10 - 80.0 mm *Compound #5 Hülse 12 - 93.4 mm

Lens mounting

Lenses are fitted to a lens board by placing the shutter assembly through the front of the board and securing the shutter assembly by threading a

locknut A locknut, also known as a lock nut, locking nut, self-locking nut, prevailing torque nut,. stiff nut or elastic stop nut, is a nut that resists loosening under vibrations and torque. Prevailing torque nuts have some portion of the nut that de ...

to rear of the shutter. A front lens element will thread onto the mounted shutter and if necessary, a second lens element will thread onto the rear of the mounted shutter. This procedure can be accomplished by a camera technician, or by an end-user with the appropriate tools.

Other uses

Lens boards are used in photographic enlargers to secure an enlarging lens to the focus stage of the device. Similar to large format photographic view cameras, a lens board is utilized by some

reprographic Reprography (a portmanteau of ''reproduction'' and ''photography'') is the reproduction of graphics through mechanical or electrical means, such as photography or xerography. Reprography is commonly used in catalogs and archives, as well as in th ...

cameras in the printing industry. Lens boards may also be utilized by some medical and scientific imaging devices.

Sizes

Lens mounting

Other uses

See also