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[milesl]

I have a particularly difficult plate that was shot with an anamorphic wide angle lens that i'm tracking with Synth Eyes. It's a nodal pan. I'm working with a full app scan of the negative un-squeezed with a pixel aspect ratio of 2. The exact focal length is unknown but the VFX super suggested a value between 18 - 24. I've been plugging in values (using Known focal length) that correspond to lenses available from local rental houses (24 - 35) as well and get the pixel error down around 0.7, but i still see the 3d trackers slipping off as they move closer out to the edges. I had heard that the actual optic center on the film plate is not the center of the full app image, but is actually shifted 110 pixels to the right. In your experience, could this be causing the near-edge slippage and if so, would adding 110 to the right edge of the image fix this lens center issue?
Thank you for any suggestions.

[ssontech]

(Handled via tech support) Offcentering like this is bad and needed to be padded out, but also the shot had lens distortion as is typical for wide-angle lenses.

[milesl]

Thanks to Russ for the help on this.
A bit of info on how this ended being set up:
The shot was anamorphic, wide angle as stated above. The film scans were full app (2048x1556). This meant factoring in a 220 pixel offset to the right based on the lens offset for the soundtrack area. Initially used 110, but believe that would actually be for a 1.85 "academy" extraction. The translation to decimals was 220/2048 or .107 to the right. Ended up padding .107 left, .214 right, and added .059 top and bottom to account for the "bowtie" after undistorting. Set as a tripod shot and full automatic. Culled a couple poor trackers. Using image preparation output undistorted cineons with overscan for the inferno (this actually took 2 tries as the distortion amount wasn't quite right on the first pass, still had some right side slippage after re-tracking). Output a new track derived from the undistorted plate and everything matches up now. After the comp is done we will re-import the finished plate and add the distortion back.
Hope this workflow helps if you find yourself with a similar shot.