Precision Flange Focal Distance Measuring Kits by CinemaTechnic
Updated 10 July 2020
CinemaTechnic’s Flange Focal Distance (FFD) measuring tool for ARRI PL is unique: It is designed primarily for checking and zeroing Autocollimator Focal Plane Micrometers (FPM) and Lens Test Projectors (LTP).
Traditional FFD measuring tools, like those supplied by ARRI are designed to calibrate the mount-to-gate distance on motion picture film cameras and allow side-side and up-down movement for checking gate squareness. They must be held against the lens mount while testing. One hand holds the FFD gage, the other hand holds the ground plate on the gate (in place of the film).
For calibrating lens testing FPM and LTP measurement should only be in the center of the mount. Our flange design self-centers and locks in the PL mount so you do not have to support it. You have your hands free to set zero on the micrometer. This is particularly important with the original analog Richter Cine M-2 Focal Plane Micrometer. Otherwise you would need three hands to set zero.
This design feature is also useful if you need to calibrate FFD on film cameras with a fine-adjustment feature, such as Moviecam Compact, SL and ARRICam. Normally you need an assistant to do that procedure.
The base of our flange is flat and is designed to be compatible with the original small diameter ARRI 52mm gage cylinders, as well as newer gage cylinders with larger diameter.
Our flange is unique in that it can also be used to calibrate IMS (Interchangeable Lens System) and EF mounts.
Another unique feature of our PL flange is that it is offered in both DIN (Deutsches Institut for Normung, 8mm stem) and AGD (American Gage Design, 0.375in stem) versions. All ARRI FFD kits came with DIN dial gages.
We can convert your original ARRI Standard/Bayonet FFD gage to PL using the original dial gage and 52mm gage cylinder.
AGD gages are by far the most common in the U.S. and readily available. The AGD version of the flange makes it possible to use new AGD gages, including digital versions. A custom brass collet holds the gage stem preventing damage to the stem or uneven pressure that can cause “sticky” gage operation.
We also offer special converter depth rods that adapt easily available AGD style tips (#4-48 NF thread) to DIN gages (M2.5 thread).
The flanges are CNC machined from steel, ground and lapped. Each is individually inspected. Flatness tolerance is 0.0002 in [0.005 mm].
Each ARRI 52mm gage cylinder we supply comes with a calibration decal showing its exact length. If there is any error from 52.000 mm, it is easily and accurately compensated by adjusting the bezel of the dial gage. The included instructions explain this procedure.
In addition to PL mount, our measuring flange can also be used with IMS and EF mounts with the appropriate depth rods and calibration standards. This is a new application, so please inquire via email (see below) if you have this requirement.
These items are custom manufactured in small batches to ensure the highest quality. Each item is individually inspected using super-precision test equipment. All components are Made in USA except the gage cylinder (ARRI Germany), DIN dial gages – we typically supply Kafer gages (Germany), and AGD dial gages – we typically supply Mitutoyo (Japan).
These kits are made in small batches. To avoid delays in fulfillment, we suggest you get in touch and let us know if you are invested in an FFD kit, even if you do not plan an immediate purchase.
Please contact us via email for more information:
If you have an original ARRI FFD kit that you no longer need and wish to sell, please email using the address above.
NOTE regarding Richter analog M-2 FPM: It is impossible to set the ceramic reflector to perfect perpendicularity. If you purchased your M-2 unit used, you can be sure that there is significant “tumble” in your reflector as you turn the micrometer.
We can calibrate your Richter analog M-2 to minimize mirror “tumble” but the it can not be reduced to much less than 2.5 arc minutes. For this reason it is important that when measuring FFD on an analog M-2, the measurement point cannot move. This is why we do not recommend standard film camera style FFD gages, such as the original ARRI gages, for calibrating the Richter M-2.
©2020 Jorge Diaz-Amador, all rights reserved