Motion Mount & Lens compatibility.

[Rob Skates]

We were rather surprised that a comprehensive list of Motion Mount incompatible lenses doesn't exist. (if one exists, we couldn't locate it) At one point we contacted RED in attempt to get a technical drawing of the motion mount or at the very least the precise flange to glass distance. We we told that they do not have a tech drawing and did not know the distance. Seriously that is what we were told. Odd considering technical drawings are even used as part of the packaging art on many RED products. Perhaps the rep was confused about what we were asking for. We discovered the hard way that the ZEISS T2.1 16mm will damage the motion mount glass. Here are some approximate measurements of the flange to rear element/cone for ZEISS T2.1 & T1.3 lenses. PLEASE NOTE: THE MEASUREMENTS ARE APPROXIMATE! Without knowing the precise flange to glass distance of the mount and the exact flange to rear elements distance of the lenses it is impossible to ensure compatibility.

ZEISS T2.1 @ INF
16mm - 29.20mm *(KNOWN TO DAMAGE THE MOTION MOUNT GLASS)
20mm - 27.12mm
24mm - 28.48mm
32mm - 30.13mm *(REPORTED TO CAUSE DAMAGE IN AN ABOVE POST)
50mm - 20.73mm
85mm - 20.73mm

10mm - 23.80mm
12mm - 28.66mm
14mm - 24.15mm

ZEISS T1.3 @ INF
18mm - 25.12mm
25mm - 24.89mm
35mm - 26.42mm
50mm - 23.00mm
85mm - 15.48mm

Again these measurements are approximate. The 16mm T2.1 and the 32mm T2.1 are known to be incompatible with the motion mount. What we are not sure of is the exact distance from the flange to the motion mount glass. The 12mm T2.1 and the 24mm T2.1 are both less than a mm shorter that the 16mm. Is that enough to clear? We have no idea and haven't chanced it. With the popularity of vintage glass and the nature of the rental environment it would seem that damage would be more frequent. We warn RED owners when they rent lenses from us that some have been know to damage motion mounts and to take care if they have the mount installed etc.

 

[Tom Taugher]

I had a similar issue with Cooke Speed Panchros:

[h=4]18 mm - T2.2 - CF 5.75 in - ⌀80 - 1.3 lbs (Will Damage Motion Mount Glass)
25 mm - T2.2 - CF 5.75 in - ⌀80 - 1.25 lbs
32 mm - T2.3 - CF 6.5 in - ⌀80 - 1.2 lbs (Will Damage Motion Mount Glass)
40 mm - T2.3 - CF 7 in - ⌀80 - 1.6 lbs
50 mm - T2.3 - CF 8 in - ⌀80 - 1.95 lbs
75 mm - T2.3 - CF 16 in - ⌀80 - 2.1 lbs
100 mm - T2.8 - CF 16.5 in - ⌀80 - 3 lbs[/h]

 

[Chad Lancaster]

a tool like this (made for leica r lenses to see if the mirror hits on canon cameras) would be good for you to know for certain