DENZ FDC Multi. A Back Focus Gauge For Various Lens Mount Types

Checking a camera’s flange focal distance (back focus) with FDC Multi provides an exact indication of the amount & direction (+ and -) of the deviation between the currently set flange focal distance and the ideal flange focal distance.
This allows you to determine the combination of adjustment foils (shims) needed to correct the flange focal distance. The slow trial and error approach to correcting the flange focal distance is now no longer necessary.
As one of the most popular DENZ products the FDC Multi is a must have for anyone who needs exactly adjusted cameras. International leading camera manufactures are using this measurement tool to calibrate their cameras before delivery.
The FDC Multi can be powered by a mains adapter (AC 100-240V; 50-80 Hz; 300 mA // out: 5V; 1.5 A) Alternatively a DC 3V battery can be used. This makes the FDC Multi very attractive for use on set, bringing laboratory accuracy to the field. To save battery power, the FDC-multi has an automatic power off function.
When the FDC Multi is mounted on your camera you can start the measuring procedure. The flange depth of PL mounts can be measured directly. For those cameras using mounts for lenses with shorter flange focal distances, such EF-, MFT-, E- und F-Mount, one of the provided adapters is used. These adapters do not change the measurement accuracy. Because the FDC Multi can be used with a variety of mounts it becomes very cost effective.
Evaluating the flange focal depth is based on projecting a red bar and a pair of green bars from different optical axis onto the camera sensor chip. At the right distance from the projective system a red bar comes to lie right between two green bars providing a symmetrical image that can be viewed on a monitor connected to the video output of the camera.
If the flange focal depth of the camera being checked is correct (namely 52.00mm in case of a PL mount camera) the FDC Multi’s scale ring attached to the hand wheel will show that “0” correction is necessary, and the combined image will be symmetrical.
If the flange focal depth is not correct, the hand wheel of the FDC Multi is turned, changing the position of the projective system along the optical axis until the combined image is symmetrical again. The required amount and direction of correction, that must be applied to the camera mount, can be read from the scale ring. The adjustment of the flange focal depth itself involves adding or removing a combination of shims under the camera mount. Thanks to the exact measurement provided by FDC Multi, painful trial and error procedures are history.
Please note, that the EF, and F-mount-adapters do not enable you to use PL lenses on Canon EF/EFS- respectively Nikon F-mount cameras.